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United States 
Environmental Protection 
Agency 


Office of Research and 
Development 
Washington DC 20460 


EPA/600/R-98/048 
December 1998 


■S-EPA Oxygenates in Water: 

Critical Information and 
Research Needs 












EPA/600/R-98/048 
December 1998 


Oxygenates in Water: 
Critical Information 
and Research Needs 


Office of Research and Development 
U.S. Environmental Protection Agency 
Washington, DC 20460 


Printed on Recycled Paper 


Disclaimer 


This document has been reviewed in accordance with U.S. Environmental Protection 
Agency policy and approved for publication. Mention of trade names or commercial products 
does not constitute endorsement or recommendation for use. 


Pv Ois 


Table of Contents 


Page 

U.S. Environmental Protection Agency Task Group . v 

External Reviewers . ix 

Preface . xi 

1. INTRODUCTION. 1 

2. SOURCE CHARACTERIZATION. 5 

2.1 Background . 5 

2.2 Needs. 8 

3. TRANSPORT . 9 

3.1 Background . 9 

3.2 Needs. 10 

4. TRANSFORMATION. 11 

4.1 Background . 11 

4.2 Needs. 12 

5. OCCURRENCE. 13 

5.1 Background . 13 

5.2 Needs. 18 

6. EXPOSURE. 19 

6.1 Background . 19 

6.2 Needs. 22 

7. AQUATIC TOXICITY . 23 

7.1 Background . 23 

7.2 Needs. 23 

8. HEALTH EFFECTS . 24 

8.1 Background . 24 

8.2 Needs. 25 

9. RELEASE PREVENTION. 26 

9.1 Background . 26 

9.2 Needs. 29 


in 































Table of Contents 

(cont’d) 

Page 

10. CONTAMINANT REMOVAL . 29 

10.1 Background. 29 

10.2 Needs . 33 

10.2.1 Remediation Needs. 34 

10.2.2 Drinking-Water Treatment Needs. 35 

11. CONCLUSIONS. 37 

REFERENCES. 39 

APPENDIX 1: Chemical Properties of Selected Oxygenates. 49 

APPENDIX 2: Current Projects Related to Oxygenates in Water. 51 


IV 












U.S. Environmental Protection Agency Task Group 


Principal Authors 

J. Michael Davis (Chair) 

Office of Research and Development 
National Center for Environmental 
Assessment 

Research Triangle Park, NC 27711 
John Brophy 

Office of Air and Radiation 
Office of Mobile Sources 
Washington, DC 20001 

Robert Hitzig 

Office of Solid Waste and Emergency 
Response 

Office of Underground Storage Tanks 
Washington, DC 20460 

Fran Kremer 

Office of Research and Development 
National Risk Management Research 
Laboratory 

Cincinnati, OH 45268 

Michael Osinski 
Office of Water 

Office of Groundwater and Drinking Water 
Washington, DC 20460 

James D. Prah 

Office of Research and Development 
National Health and Environmental 
Effects Research Laboratory 
Research Triangle Park, NC 27711 

Contributors 

Dorothy Canter 

Office of Solid Waste and Emergency 
Response 

Office of the Assistant Administrator 
Washington, DC 20460 


Stephen Schmelling 
Office of Research and Development 
National Risk Management Research 
Laboratory 

Ada, OK 74821-1198 
Thomas F. Speth 

Office of Research and Development 
National Risk Management Research 
Laboratory 

Cincinnati, OH 45268 
Robert Swank 

Office of Research and Development 
National Exposure Research Laboratory 
Athens, GA 30605-2720 

Anthony N. Tafuri 
Office of Research and Development 
National Risk Management Research 
Laboratory 
Edison, NJ 08837 

Candida West 

Office of Research and Development 
National Risk Management Research 
Laboratory 

Ada, OK 74821-1198 


Stanley Durkee 

Office of Research and Development 
Office of Science Policy 
Washington, DC 20460 


v 


U.S. Environmental Protection Agency Task Group 

(cont’d) 


Contributors (cont’d) 

Jackson Ellington 

Office of Research and Development 
National Exposure Research Laboratory 
Athens, GA 30605-2720 

Charles Freed 
Office of Air and Radiation 
Office of Mobile Sources 
Washington, DC 20001 

Frank Gostomski 
Office of Water 

Office of Science and Technology 
Washington, DC 20460 

Judith A. Graham 

Office of Research and Development 
National Exposure Research Laboratory 
Research Triangle Park, NC 27711 

Matthew Hagemann 
Region 9 

San Francisco, CA 94105 

John Helvig 
Region 7 

Kansas City, KS 66101 

Roland Hemmet 
Region 2 

New York, NY 10007-1866 

Robert W. Hillger 
Region 1 

Boston, MA 02203 
Kenneth T. Knapp 

Office of Research and Development 
National Exposure Research Laboratory 
Research Triangle Park, NC 27711 


Amal Mahfouz 
Office of Water 

Office of Science and Technology 
Washington, DC 20460 

Michael Moltzen 
Region 2 

New York, NY 10007-1866 

Richard Muza 
Region 8 

Denver, CO 80202 
Charles Ris 

Office of Research and Development 
National Center for Environmental 
Assessment 

Washington, DC 20460 

Bill Robberson 
Region 9 

San Francisco, CA 94105 
Gary Timm 

Office of Prevention, Pesticides, and 
Toxic Substances 
Washington, DC 20460 

Jim Weaver 

Office of Research and Development 
National Exposure Research Laboratory 
Athens, GA 30605-2720 

Lester Wybomy II 
Office of Air and Radiation 
Office of Mobile Sources 
Ann Arbor, MI 48105-2498 


vi 


U.S. Environmental Protection Agency Task Group 

(cont’d) 


Members 
Charles Auer 

Office of Prevention, Pesticides, and 
Toxic Substances 
Washington, DC 20460 

Ben Blaney 

Office of Research and Development 
National Risk Management Research 
Laboratory 

Cincinnati, OH 45268 
Dave Brown 

Office of Research and Development 
National Exposure Research Laboratory 
Athens, GA 30605-2720 

Rebecca L. Calderon 
Office of Research and Development 
National Health and Environmental Effects 
Research Laboratory 
Research Triangle Park, NC 27711 

Tudor Davies 
Office of Water 

Office of Science and Technology 
Washington, DC 20460 

Joe A. Elder 

Office of Research and Development 
National Health and Environmental Effects 
Research Laboratory 
Research Triangle Park, NC 27711 

William H. Farland 
Office of Research and Development 
National Center for Environmental 
Assessment 

Washington, DC 20460 


Rene Fuentes 
Region 10 
Seattle, WA 98101 

Lester D. Grant 

Office of Research and Development 
National Center for Environmental 
Assessment 

Research Triangle Park, NC 27711 
Fred Hauchman 

Office of Research and Development 
National Health and Environmental Effects 
Research Laboratory 
Research Triangle Park, NC 27711 

Steven F. Hedtke 

Office of Research and Development 
National Health and Environmental Effects 
Research Laboratory 
Duluth, MN 

John Heffelfinger 

Office of Solid Waste and Emergency 
Response 

Office of Underground Storage Tanks 
Washington, DC 20460 

Ronald Landy 
Region 3 

Philadelphia, PA 19107 
Maureen Lewison 

Office of Solid Waste and Emergency 
Response 

Office of Underground Storage Tanks 
Washington, DC 20460 


Vll 


U.S. Environmental Protection Agency Task Group 

(cont’d) 


Members (cont’d) 

Dennis McChesney 
Region 2 

New York, NY 10007-1866 

John Mooney 
Region 5 

Chicago, IL 60604-3507 
Margo Oge 

Office of Air and Radiation 
Office of Mobile Sources 
Washington, DC 20460 

Charles Sands 

Office of Solid Waste and Emergency 
Response 

Washington, DC 20460 

Paul Scoggins 
Region 6 

Dallas, TX 75202-2733 


Winona Victery 
Region 9 

San Francisco, CA 94105 

Michael Watson 
Region 10 
Seattle, WA 98101 

Jeanette Wiltse 
Office of Water 

Office of Science and Technology 
Washington, DC 20460 

Lynn Wood 

Office of Research and Development 
National Risk Management Research 
Laboratory 

Ada, OK 74821-1198 

Donn Zuroski 
Region 9 

San Francisco, CA 94105 


vm 


External Reviewers* 


David Ashley 

National Center for Environmental Health 
U.S. Centers for Disease Control and 
Prevention 

Atlanta, GA 30341-3724 

Bruce Bauman 

American Petroleum Institute 

Washington, DC 20005-4070 

Steven Book 

California Department of Health Services, 
Drinking Water 
Sacramento, CA 94234-7320 

Robert Borden 

North Carolina State University 
Raleigh, NC 27695 

Susan Borghoff 

Chemical Industry Institute of Toxicology 
Research Triangle Park, NC 27709-2137 

Herb Buxton 

Toxic Substances Hydrology Program 
U.S. Geological Survey 
West Trenton, NJ 08628 

Maria Costantini 
Health Effects Institute 
Cambridge, MA 02139-3180 

James S. Crowley 

Santa Clara Valley Water District 

San Jose, CA 95118-3686 

Joan Denton 

California Air Resources Board 
Sacramento, CA 95814 

Gary Ginsberg 

Connecticut Department of Public Health 
Hartford, CT 06134-0308 


Bernard Goldstein (Workshop Chair) 
Department of Environmental Community 
Medicine 

Environmental and Occupational Health 
Sciences Institute 
Piscataway, NJ 0885-1179 

Anne Happel 

Environmental Restoration Division 
Lawrence Livermore National Laboratory 
Livermore, CA 94551 

Carol Henry 

American Petroleum Institute 
Washington, DC 20005-4070 

Michael Kavanaugh 
Malcolm Pimie, Inc 
Oakland, CA 94612 

John Kneiss 

Oxygenated Fuels Association 
Arlington, VA 22209 

Jerold Last 

UC Toxic Substances Research and 
Teaching Program 
University of Califomia-Davis 
Davis, CA 95616-8723 

Ronald Melnick 

National Institute of Environmental Health 
Sciences 

Research Triangle Park, NC 27709 

James Pankow 
Oregon Graduate Institute 
Portland, OR 97291-1000 

Hari Rao 

Edison, NJ 08820 


ix 


External Reviewers 

(cont’d) 


Thomas Skower 
Underwriters Laboratories, Inc. 
Northbrook, IL 60062 

Arthur Stewart 

Oak Ridge National Laboratory 
Oak Ridge, TN 37831-6036 

John H. Sullivan 
Government Affairs Office 
American Water Works Association 
Washington, DC 20005 

Robert Tardiff 
Sapphire Group, Inc. 

Bethesda, MD 20814 


Barbara Walton / Rosina M. Bierbaum 
Office of Science and Technology 
Policy - Environment Division 
Executive Office of the President 
Washington, DC 20502 

Clifford Weisel 

Exposure Measurement and Assessment 
Division 

Environmental and Occupational Health 
Sciences Institute 
Piscataway, NJ 08855-1179 

John Zogorski 
U.S. Geological Survey 
Water Resources Division 
Rapid City, SD 57702 


*These individuals provided technical review comments by invited participation in a review workshop 
held on October 7, 1997 and/or by written submissions. 


x 


Preface 


The purpose of this document is to identify key issues related to assessing and managing the 
potential health and environmental risks of oxygenate contamination of water. Oxygenates are 
chemicals added to fuels (“oxy fuels”) to increase the oxygen content and thereby reduce 
emissions from use of the fuel. This document builds on and extends an earlier report, Oxyfuels 
Information Needs (U.S. Environmental Protection Agency, 1996), which included water issues 
but tended to focus more on inhalation health risk issues. The present document focuses on those 
gaps and limitations in current information that constitute the most critical and immediate needs to 
be addressed in support of risk assessment and risk management efforts related to oxygenates in 
water. This document is primarily intended to serve as a starting point and general guide to 
planning future research. It is not a comprehensive review of issues pertaining to oxygenates in 
water, nor does it describe in detail specific studies or projects that are needed. 

Efforts to address many of the needs identified in this document have already begun or are 
under consideration by various organizations. A current listing of such projects may be found in 
Appendix 2. 


xi 






















1. INTRODUCTION 


Contamination of ground and surface waters by motor vehicle fuels and fuel additives is not 
a new problem, given the history and pervasive use of fuels in the 20th century. Well over a 
million underground fuel storage tanks exist in the United States, and leaks from these tanks have 
been the focus of major programs to prevent or clean up such releases. Transport of fuels via 
pipelines and in bulk containers also presents the potential for accidental releases and consequent 
environmental contamination. Experience suggests that contamination from these and other 
sources of fuel releases can affect water quality and the biota that depend upon the water, 
including human populations. 

Against this background of experience with fuel-related contamination of ground and 
surface waters, recent events have focused attention on what appear to be somewhat different 
characteristics associated with fuels containing chemicals known as oxygenates. Oxygenates are 
added to fuel to increase its oxygen content and thereby reduce certain emissions from use of the 
fuel. Of the several ethers and alcohols that may serve as oxygenates, methyl tertiary butyl ether 
(MTBE) is the most frequently used. Monitoring of groundwater quality by the U.S. Geological 
Survey (USGS) indicates that MTBE has become detectable in shallow groundwater samples in 
certain urban areas in recent years, with concentrations ranging from below the reporting level of 
0.2 pg/L 1 to over 20,000 pg/L (Squillace et al., 1996). Reports of point-source MTBE 
contamination of drinking water sources at well over 100 pg/L, including aquifers serving as the 
primary source of drinking water for the city of Santa Monica, CA (California Department of 
Health Services, 1998), raise several important questions about potential environmental and public 
health impacts of oxygenated fuels. 

A key question is whether oxygenates in water pose a significant threat to human health or 
the environment. To assess the risks of MTBE or any other oxygenate, the potential for exposure 
to, and effects of, the contaminant(s) must be characterized. However, only limited information 
exists for characterizing the possible risks of oxygenates in water. For example, the extent of 
population exposures to MTBE in drinking water is unknown. Even in cases where MTBE is 
clearly present in public or private water supplies, limited guidance exists for determining levels 


1 1 pg/L = 1 part per billion (ppb). 


1 



that would be acceptable or unacceptable from the standpoint of public health or consumer 
acceptability. The U.S. Environmental Protection Agency (EPA) Office of Water has released a 
Drinking Water Advisory for MTBE (U.S. Environmental Protection Agency, 1997). As the full 
title of the document indicates, it provides “Consumer Acceptability Advice and Health Effects 
Analysis on [MTBE].” The Advisory “recommends that keeping levels of contamination in the 
range of 20 to 40 fig/L or below to protect consumer acceptance of the water resource also 
would provide a large margin of exposure (safety) from toxic effects.” However, the document 
discusses “many uncertainties and limitations associated with the toxicity data base for this 
chemical” and notes the consequent difficulty in estimating a health protection level for MTBE in 
drinking water. The uncertainties in assessing the health risks of MTBE are reflected somewhat 
in the various guidance values (e.g., advisories, action levels, standards) that have been issued by 
individual states, ranging at one time from 35 pg/L in California to 230 pg/L in Illinois 
(Interagency Oxygenated Fuels Assessment Steering Committee, 1997). As efforts to assess 
health risks and derive guidance values continue at the local, state, and federal levels, the need for 
an adequate scientific foundation for these efforts intensifies. Without more definitive scientific 
infonnation, uncertainties will continue to dominate risk assessments of oxygenates. 

If it is concluded that a risk or problem exists, other questions face risk managers in 
formulating actions to address oxygenate contamination of water. For example, What are the 
sources of contamination? How long is it likely to persist? How widespread is the 
contamination? What cost-effective methods exist to remove the contaminant(s) from water? 
and, How can further contamination be avoided? A recent review of fuel oxygenates and water 
quality (Interagency Oxygenated Fuels Assessment Steering Committee, 1997) notes that for 
various reasons, including the potentially greater persistence of MTBE in ground water than other 
components of gasoline, remediation of MTBE-contaminated ground water may pose unique 
problems. The Interagency Assessment also notes the possibility that ground water could be 
contaminated by deposition of oxygenates from the ambient atmosphere. A quantitative answer 
to whether non-point sources or point sources, such as leaking underground storage tanks 
(USTs), pose a greater potential risk of environmental contamination is not available. 

Risk assessment and risk management require information that is generally obtained through 
research, data collection, or analysis of data that already exist. The purpose of this document is to 
identify the key information needed to assess and manage the potential health and environmental 


2 


risks related to oxygenates in water. This document builds on an earlier report, Oxyfuels 
Information Needs (U.S. Environmental Protection Agency, 1996), which encompassed water 
issues but tended to emphasize inhalation health risk issues. As noted in Oxyfuels Information 
Needs, the benefits and risks of any given oxyfuel must be assessed in relation to an alternative, 
such as conventional gasoline. A comparative assessment of the potential risks or benefits of any 
given fuel in relation to any other fuel is obviously a complex, multifaceted endeavor (see U.S. 
Environmental Protection Agency, 1992). The present document is much more limited in scope. 

It focuses on key information required to support the most pressing risk assessment and risk 
management needs pertaining to oxygenates in water, with the aim of achieving progress more 
readily than would be possible by attempting to cover every possible issue in a comprehensive 
manner. However, one should not lose sight of the broader and perhaps ultimate issue of the need 
to examine quantitatively the trade-offs between sought improvements in air quality through the 
use of oxygenates and possible reductions in water quality through oxygenate contamination. 

This document is primarily intended to serve as a starting point and general guide to 
planning research related to oxygenates in water. It does not attempt to describe in detail specific 
studies and projects that are needed. Nor is this document a formal assessment of environmental 
or health risks associated with oxygenates or an in-depth analysis of candidate risk management 
options for addressing this problem. Other reports are available for more detailed reviews of the 
health and environmental effects of oxygenates (e.g., U.S. Environmental Protection Agency, 
1993, 1994; Health Effects Institute, 1996; Interagency Oxygenated Fuels Assessment Steering 
Committee, 1996, 1997; National Research Council, 1996), particularly the “Water Quality” 
chapter from the Interagency Assessment of Oxygenated Fuels (Interagency Oxygenated Fuels 
Assessment Steering Committee, 1997). Note that all of these reports have pointed out the lack 
of adequate information to assess fully and definitively the risks and benefits associated with 
oxyfuels in comparison to conventional fuels. 

Some brief background information on why fuel oxygenates are used may be helpful. 

The 1990 Clean Air Act Amendments (CAAA) created two fuel programs to be administered by 
EPA requiring use of oxygenates (U.S. Code, 1990). The first program began in the fall of 1992 
with the objective of reducing carbon monoxide (CO) emissions in several areas of the country 
where the National Ambient Air Quality Standard (NAAQS) for CO was exceeded. Under this 
program, the CAAA required the sale of gasoline with an oxygen content of 2.7% by weight 


3 


during the cold weather season in designated areas that failed to attain the NAAQS for CO. 

The second program required the year-round use of reformulated gasoline (RFG) containing 
2.0% oxygen by weight, beginning in 1995, in selected areas having the highest levels of 
tropospheric ozone. In addition to reducing emissions of ozone precursors, the RFG program 
also was intended to help reduce the emissions of certain toxic organic air pollutants. 

Collectively, cold-weather oxygenated gasoline and year-round RFG with oxygenate may be 
referred to as “oxyfuels.” 

Although MTBE and, to a lesser extent, ethanol currently dominate the marketplace, no 
specific oxygenate is required or designated by the 1990 CAAA. Several other ethers and 
alcohols also may serve as oxygenates and could become more prevalent, depending on various 
factors such as cost, ease of production and transfer, and blending characteristics. These 
oxygenates include ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether (TAME), tertiary 
amyl ethyl ether (TAEE), diisopropyl ether (DIPE), dimethyl ether (DME), and tertiary butanol 
(TBA). The chemical properties of several oxygenates are listed in Appendix 1. To achieve the 
specified oxygen content requirements, approximately 15%-vol MTBE or 7.5%-vol ethanol can 
be used to yield the 2.7%-wt oxygen for the winter fuel program and approximately 11%-vol 
MTBE or 5.5%-vol ethanol for the 2.0%-wt oxygen required by the RFG fuel program. 

According to EPA’s Office of Mobile Sources, about 30% of U.S. gasoline currently 
contains some form of oxygenate for air quality improvement purposes. Beginning in the late 
1970s, MTBE and ethanol were used to increase the octane value of gasoline in the United States 
as lead was phased out. Approximately 25% or more of U.S. fuel may have contained MTBE or 
ethanol as an octane-enhancer in a given year, but the current usage of MTBE for octane is 
considerably lower, constituting perhaps 3 to 5% of the fuel supply. These levels of usage are 
subject to alteration as economic variables (e.g., the price of crude oil) and other factors change. 
The concentration of MTBE used for octane purposes in conventional gasoline may vary widely 
up to an allowable limit of 15%-vol MTBE, depending on other constituents and properties of the 
fuel, but likely is more on the order of 1 to 8%-vol MTBE. Gasoline containing 10% ethanol, 
often referred to as “gasohol,” represents about 10% of all gasoline sold in the United States, but 
may be much more prevalent in certain locales, particularly in the Midwest. More than 
10 billion kg MTBE was used in U.S. gasoline in 1996, and fuel ethanol use was about 3 billion 
kg (DeWitt & Company, Incorporated, 1997). 


4 


This document applies to all ether and alcohol oxygenates unless otherwise stated. It refers 
more to MTBE because of its predominant use and because more information is available for 
MTBE than for other ethers and alcohols (except perhaps for ethanol). Nevertheless, it should 
not be inferred that the only oxygenate warranting attention is MTBE or, for that matter, that the 
issues identified here are necessarily unique to oxyfuels. 

This document is organized around the following headings: 

• Source Characterization 

• Transport 

• Transformation 

• Occurrence 

• Exposure 

• Aquatic Toxicity 

• Health Effects 

• Release Prevention 

• Contaminant Removal 

Within each of these areas, a brief background section highlights available information on key 
issues, followed by a section that identifies research or other information gaps that emerge as 
needs. Note that the grouping of topics is somewhat arbitrary. The overlap in various areas 
should be seen as a potential benefit in terms of combining objectives and resources for projects 
that can be feasibly and appropriately linked. Such leveraging of resources could extend across 
organizational boundaries as well. 


2. SOURCE CHARACTERIZATION 

2.1 Background 

Releases of fuel oxygenates occur during manufacture, distribution, storage, and use, 
particularly from point sources such as USTs, pipelines, and refueling facilities. According to the 
Toxics Release Inventory (TRI), releases of MTBE from production sources in the United States 
amounted to approximately 1.7 million kg in 1996 (U.S. Environmental Protection Agency, 
1998a). Of this total, about 97% was released to the air and less than 3% was discharged to 


5 



surface water. For mobile sources, assuming 10 billion kg MTBE used in gasoline (DeWitt & 
Company, Incorporated, 1997) and an average U.S. corporate fleet emission rate of 
approximately 3.6 mg MTBE per gram MTBE in fuels (Wybomy, 1997, 1998), total motor 
vehicle emissions of MTBE in 1996 would have been on the order of 40 million kg in the United 
States. 

Impacts to water resources can be loosely grouped into two categories: (1) widespread 
impacts occurring at low concentrations and (2) local impacts occurring at high concentrations. 
The first group is often the result of indirect sources, such as vehicular emissions of oxygenates 
that dissolve in rainfall and subsequently infiltrate to ground water, and may be spread over large 
areas. Also, leakage from motorized recreational water craft can be considered a diffuse source 
of contamination of surface water bodies such as reservoirs. The second category results from 
direct releases to surface and ground water from such sources as leaking USTs, pipelines, or tank 
cars. 

Oxygenates in the atmosphere degrade with a half-life as short as 3 days (Smith et al., 1991; 
Wallington et al., 1988). However, MTBE is soluble in water and, because of its relatively low 
Henry’s Law constant, partitions readily from air to rainfall and snowfall. The concentration in 
precipitation is determined primarily by the concentration in the atmosphere, the Henry’s Law 
constant at a given air temperature, the time that the precipitation is exposed to MTBE, and other 
characteristics of the precipitation that determine contact efficiency, e.g., rain droplet size and 
snowflake surface area (Hoff et al., 1998). This process could result in deposition to land surface 
and subsequent contamination of surface and ground water. Also, MTBE could accumulate in 
snow at sites such as service stations, parking lots, and city streets and be released as a pulse 
source to soil or ground water as the snow melts. The detection of MTBE in 41 (7%) of 
592 stormwater samples collected in 16 cities and metropolitan areas from 1991 to 1995, with the 
highest percentage of detections found in samples collected during high MTBE usage winter 
months (Delzer et al., 1996), is consistent with atmospheric washout of MTBE in rain or snow to 
the ground surface. Measured concentrations of MTBE in the stormwater samples ranged from 
0.2 to 8.7 pg/L, with a median of 1.5 pg/L. Modeling calculations have predicted MTBE 
concentrations in rainwater ranging from <1 pg/L to 3 pg/L, within the range of concentrations 
actually found in groundwater samples (Interagency Oxygenated Fuels Assessment Steering 
Committee, 1997). Also, modeling of the transport of MTBE from land surface to water table by 


6 


the infiltration of rain water, for a variety of infiltration and evapotranspiration scenarios, suggests 
that the concentration of MTBE in groundwater two meters below the water table can range from 
zero to almost 200 percent of the concentration in the rain water (Pankow et al., 1997). The use 
of shallow ground water for public and private water supplies makes such nonpoint contamination 
a potential public health issue as well as an environmental quality issue. 

Direct releases of MTBE and other fuel oxygenates to surface and groundwater sources of 
drinking water also occur. The majority of direct releases of MTBE to surface water reported to 
TRI were attributable to only a few petroleum product facilities. However, refueling and 
operation of boats and other recreational water craft also are suspected as significant sources of 
releases of MTBE to surface waters in heavily used recreational areas. Detections of MTBE in 
some drinking water reservoirs in California have prompted studies on the input of MTBE to 
surface waters via recreational watercraft, precipitation, and snowmelt runoff (e.g., Reuter et al., 
1998; Dale et al., 1997). Other possible sources of MTBE releases to surface water could include 
wastewater treatment operations at petroleum operations and publicly owned treatment works. 

Leaking USTs are believed to be the primary source of localized releases of MTBE in high 
concentrations. According to EPA’s Office of Underground Storage Tanks (OUST), nearly 
1 million federally regulated USTs are currently in use at approximately 360,000 facilities in the 
United States. Not all of these USTs contain oxy fuels or gasoline with MTBE or ethanol as 
octane enhancers, but it can be roughly estimated that about 50% of the gasoline sold in the 
United States in recent years has contained MTBE or ethanol (U.S. Department of Energy, 1995). 
Some of the earliest documented UST releases involving MTBE occurred in Maine in the 
mid-1980s (Garrett, 1987). More recently, drinking water wells in Santa Monica, CA, were shut 
down because of MTBE contamination from one or more leaking USTs (Geraghty & Miller, 
Incorporated, 1996). Since 1988, 330,000 confirmed releases from regulated USTs have been 
reported to EPA/OUST. Based on historical trends, OUST estimates that 100,000 additional 
releases will be reported during the next few years as existing USTs are upgraded, closed, or 
replaced. This estimate does not include an even greater number of federally unregulated storage 
tanks. Although EPA regulations (§280.21, Code of Federal Regulations, 1990) require that all 
USTs be upgraded, closed, or replaced by December 1998, current estimates indicate that 25 to 
35% of USTs will not be in compliance by that date. 


7 


Despite recent and ongoing studies, it is not clear whether the greater impact from MTBE 
or other fuel oxygenates to ground water is from diffuse or point sources (i.e., what fraction of 
the MTBE or other oxygenate load and exposure is diffuse [e.g., from precipitation] or is related 
specifically to spills or leaks from fuel containers). Although relatively high groundwater 
concentrations may be readily associated with point source releases, concentrations on the order 
of 10 pg/L or lower could be associated with nonpoint sources as well as point sources 
(Interagency Oxygenated Fuels Assessment Steering Committee, 1997). 

2.2 Needs 

A model linking air to land to surface water and ground water fate for oxygenates needs to 
be developed and tested. Such an airshed-watershed model could be used to conduct ecosystem 
exposure assessments, serve as a key input to human exposure assessments, design management 
and remediation strategies, and assist in source identification and apportionment. In particular, 
the model could be used to predict upper limit values of surface and ground water concentrations 
from ambient sources that could be compared to measured values, such as those expected from 
the ongoing USGS study at Glassboro, NJ (Baehr and Ayers, 1997). A recent review of the 
environmental behavior and fate of MTBE by Squillace et al. (1997) summarizes important 
transport and transformation processes that must be included in such a model. The model could 
build on recent work by Pankow et al. (1997) and Malcolm Pimie, Incorporated (1998a) on 
modeling the ground water impacts from atmospheric washout and surface water impacts from 
the use of two-stroke engines. The model also could be used to estimate snow blanket buildup of 
oxygenates and subsequent release at first thaw, with the results then compared to data from field 
studies as a test of this potential pulse loading mechanism in a watershed. Once this modeling 
tool is developed and tested, it could be used to provide a national estimate of ambient 
contributions to surface and shallow ground water. It also could be used to provide point and 
non-point source aggregate concentrations within specific watersheds as a function of time 
(season) for total exposure assessment purposes. 

The relative loads or fluxes of the oxygenates to surface and ground waters from point 
sources versus diffuse (nonpoint) sources must be more accurately determined. A possible 
approach to addressing this need might be the identification of a “source signature” for 
oxygenates that would permit reliable source identification, and perhaps even source 


8 


apportionment, when used in conjunction with fate models. Although the identification of a 
source signature would be very useful, the feasibility of doing so is unclear, and attempts to 
provide similar signatures for other environmental contaminates do not provide much cause for 
optimism. Consequently, this has to be rated as a lower priority than the development of the 
multimedia model described above. 


3. TRANSPORT 

3.1 Background 

Oxygenates may enter both surface and ground water from diffuse and point sources (see 
Section 2, Source Characterization). In the case of scavenging from the atmosphere to 
precipitation, numerical modeling by Pankow et al. (1997) indicates that MTBE would transfer 
from the unsaturated zone into the saturated zone. However, no field observations of MTBE 
concentrations in ground water during and after precipitation or snow melt events are known to 
have been conducted. 

The transport of oxygenates, particularly MTBE, through aquifers would be expected to 
occur at nearly the same velocity as the ground water. In a mixed-composition contaminant 
source, such as is found in oxygenated fuels, each individual component will travel at a rate 
dependent on its water solubility and sorption tendency for soil. Oxygenates generally are more 
soluble in water and less sorbed to soils than the other major organic compounds in gasoline, 
namely, benzene, toluene, ethylbenzene, and xylenes (BTEX). Given sufficient time and distance, 
each component of the mixture will separate within the plume according to basic chromatographic 
principles. Consequently, MTBE and other oxygenates would be expected to be at the leading 
edge of the plume or, in the extreme case over a long period of time, could become completely 
separated from the rest of the plume if the original source of oxygenate were eliminated. 

If biodegradation of the oxygenate occurs (see Section 4, Transformation), it will interact with the 
transport process such that the front may appear to recede or be stabilized. 

Generally, aquifer vulnerability to oxygenate contamination can be predicted using current 
wellhead protection models on a case-by-case basis. The required parameters for these models 
are hydrologic, geologic, and contaminant-specific. The required chemical data for modeling 


9 


oxygenate transport are generally known, but transformation rates for the subsurface soil, vadose 
zone, and aquifers are required to run these models. The vulnerability of deep aquifers to 
oxygenate contamination is not well documented. In particular, the threat to deep aquifers due to 
abandoned wells and/or karst topography has not been assessed. Similarly, the threat to surface 
streams and lakes has not been assessed, even though suitable fate models for both exist. Again, 
adequate oxygenate loading models and fate parameters are needed to apply these models, 
particularly biodegradation rates, photolysis rates, and net air-water exchange rates. 

3.2 Needs 

Given the progress made in the last several years on modeling the fate (transport and 
transformation) of organic compounds, particularly BTEX compounds, in soils, ground water, 
and surface water, reasonable estimates of transport between and through environmental media 
can be made for oxygenates. For example, MTBE is expected to move through soil and ground 
water at a higher rate than BTEX compounds because it is more water soluble and less retarded 
by the solid matrix. However, the impact that biodegradation will have on MTBE plume 
movement is less well understood. The greatest need, therefore, is to determine biodegradation 
rates for MTBE, other oxygenates, and their by-products under typical soil-groundwater transport 
conditions (as outlined in Section 4, Transformation). Field studies are needed to validate 
modeled rates of MTBE infiltration during precipitation events to determine the extent that 
diffuse sources contribute to groundwater contamination, particularly shallow aquifers used for 
private wells. Three dimensional delineation of MTBE plume morphology in a variety of 
hydrological settings can be accomplished using push sampling techniques at multiple levels. 

Deep aquifer vulnerability should be examined by applying state-of-the-art fate models for 
scenarios that include karst-fractured flow effects and abandoned wells in areas that have high 
oxygenate use. 

Field studies of the type the USGS Toxics Program (Baehr et al., 1997) is conducting are 
needed to quantify the combined impact of precipitation, land use, and storm water management 
practices on oxygenate loadings to surface and ground waters, and to develop and test multimedia 
exposure models. Stream and lake threat assessments also should be conducted to bound the 
potential threats from both diffuse and point sources of oxygenates and their degradation 
products. 


10 


4. TRANSFORMATION 


4.1 Background 

Contaminants may be transformed through a variety of chemical, physical, or biological 
processes. As a result, the mass, toxicity, mobility, volume, or concentration of parent 
contaminants in soil and water may be altered. The resulting products of these transformation 
processes may in turn pose either a greater or lesser risk. For surface water, potential 
transformation processes are biodegradation, photolysis, and hydrolysis. In ground water, the 
potential transformation processes include biodegradation and hydrolysis. In surface water, 
photolysis is the most important transformation process for ether oxygenates, and biodegradation 
is the most important process for alcohols. Basic photolytic and hydrolytic processes are 
adequately understood. 

Studies on the rates and pathways of environmental MTBE biodegradation are inconclusive, 
in part because they have been conducted under different conditions. For example, Suflita and 
Mormile (1993) reported no biodegradation of MTBE in lab microcosms under a variety of 
aerobic and anaerobic conditions, using sediments from a petroleum-contaminated site. Salanitro 
et al. (1994), however, reported complete mineralization of MTBE to C0 2 in a mixed culture that 
was continuously sparged with oxygen. In another study (Petroleum Environmental Research 
Forum, 1993), MTBE was biodegraded when inoculated with a specific bacterial enrichment but 
not when inoculated with activated sludge. Limited biodegradation was observed in sediments 
under methanogenic conditions (Mormile et al., 1994) and in aerobic microcosms constructed 
with aquifer material obtained from the vicinity of the source area of a plume of dissolved BTEX 
and MTBE (Borden et al., 1997). Steffan et al. (1997) found that a number of propane-oxidizing 
bacteria were able to degrade high concentrations of MTBE, ETBE, and TAME. A series of 
degradation products were formed but did not prove to be effective growth substrates. Marked 
reduction in the concentrations of MTBE and benzene following termination of active remediation 
of fuel contamination was observed at a site in North Carolina (Cho et al., 1997). Products of 
MTBE biodegradation have been reported to include TBA (Mormile et al., 1994), but 
comprehensive identification of biodegradation products and reaction pathways has not been 
undertaken. 


11 


Results from field studies of the natural biodegradation of MTBE in ground water show that 
the processes involved generally take place at very slow rates or with long lag times, and depend 
on site-specific geochemical conditions. Schinner and Barker (1998) found that during the first 
16 months following a controlled injection of oxygenated gasoline in a sandy aquifer in Ontario, 
there was little evidence for the biodegradation of MTBE. However, when the aquifer was 
sampled seven years later, the mass of MTBE had declined by more than an order of magnitude. 
Although the authors hypothesized that natural biodegradation may have been responsible for this 
disappearance, they noted the need for confirmatory lines of evidence to support this hypothesis. 
In contrast, Landmeyer et al. (1998) studied an accidental spill in South Carolina over a five year 
period and concluded that dispersion and dilution were primarily responsible for decreases in the 
concentration of MTBE, with biodegradation playing a very minor role. 

Ethanol may pose a different issue with respect to oxyfuel biodegradation. Recent reports 
have noted that the presence of ethanol in gasoline may inhibit the biodegradation of BTEX 
compounds in groundwater, perhaps because microbes preferentially metabolize the ethanol 
(Corseuil and Alvarez, 1996; Corseuil et al., 1996, 1998; Hunt et al., 1997). As a result, these 
BTEX plumes may persist longer and become larger. 

The above discussion is not a comprehensive summary of studies on the biodegradation of 
MTBE and other oxygenates, but it does illustrate the variety of results observed. Most of the 
studies were conducted in laboratories, and the results are not necessarily representative of what 
might occur in the field. In addition, the observed rates of degradation vary widely, and this 
variability will impact the applicability of biodegradation as a remedial option (see Section 10, 
Contaminant Removal). 

4.2 Needs 

Biodegradation rates and pathways for MTBE and other oxygenates need to be measured 
experimentally to understand and predict the fate of these compounds in the environment, and to 
design cost-effective removal and remediation technologies. The rates of biodegradation will be 
key in understanding the fate of oxygenates in the subsurface, in developing in situ and ex situ 
contaminant treatments, in implementing natural attenuation protocols, and in conducting aquifer 
vulnerability modeling. Identification of by-products and characterization of their environmental 
fate are needed to develop a complete picture of the effects of oxygenates on the environment and 


12 


consequently the risks they may pose. Natural or intrinsic bioremediation is being widely 
accepted as either a primary or “polishing” process for groundwater remediation. Rapid 
transport, coupled with a slow rate of biodegradation, if confirmed, could limit the application of 
this remediation strategy as it relates to MTBE and possibly other oxygenates. 

Additional field-scale and complementary laboratory microcosm studies are needed for sites 
with a variety of geochemical conditions and contamination scenarios. The geochemical 
conditions should reflect those commonly found in contaminated groundwater systems, including 
a range of redox and pH conditions, to determine the relative importance of aerobic and anaerobic 
processes in MTBE degradation. The contamination scenarios should include regions not only 
near the source where concentrations will be the highest but downgradient from the source where 
concentrations are likely to be much lower, as well as during vadose zone infiltration by 
contaminated storm water. The laboratory studies also should investigate the rates of 
biodegradation for high, moderate, and low concentrations of oxygenates, particularly as the 
concentration approaches a cleanup standard. Transformation products need to be identified and 
quantified so that specific biochemical pathways and degradation product yields under different 
conditions can be determined. Along this line, more attention should be given to other 
oxygenates that are not yet being used on as wide a scale as MTBE and ethanol but that could 
come into more widespread use. The possibility that ethanol or other oxygenates may inhibit the 
biodegradation of BTEX should be evaluated. 


5. OCCURRENCE 

5.1 Background 

Although scattered incidents of localized water contamination by MTBE have been reported 
since the early 1980s, the first report to suggest that oxygenate contamination of water might be 
occurring on a widespread basis came as a result of the USGS National Water Quality 
Assessment (NAWQA) program. Designed to assess the status and trends in the quality of 
ground and surface water resources of the nation, the NAWQA program began sampling ground 
waters for MTBE in 1993 (and added TAME, ETBE, and DIPE in 1996). In an initial analysis of 
the NAWQA program’s first 20 study areas or units, MTBE was the second most frequently 


13 


detected volatile organic compound (VOC) in shallow ground water from selected urban areas 
monitored during 1993 and 1994 (Squillace et al., 1996). Of 210 sampled wells and springs, 

56 (27%) contained MTBE at a minimum reporting level of 0.2 pg/L. (For comparison, 28% 
contained chloroform and 5% contained benzene.) Sixty wells and one spring contained MTBE 
and/or BTEX; of these 61 sites, 79% had MTBE alone, and 13% had both MTBE and BTEX. 

Of all the urban wells and springs sampled, 3% had MTBE concentrations exceeding 20 pg/L. 

Since the USGS findings, other studies have provided data that supplement the picture of 
MTBE occurrence in ground, surface, and drinking water. However, it is difficult to characterize 
the overall occurrence of oxygenate contamination because reports vary in their focus, methods, 
geographic coverage, and time frames. Also, some monitoring programs are ongoing, with 
reports updated continually via the internet. Therefore, this discussion can offer only an 
impressionistic treatment of the subject. Although the relative contributions of point and 
non-point sources are yet to be determined (see Section 2, Source Characterization), sites of 
known or possible UST releases obviously warrant particular attention. For example, Happel 
et al. (1998) analyzed data from 236 leaking UST sites in California and found that MTBE was 
detected at 78% of these sites. Of the 32,409 known leaking UST sites in California, 13,278 are 
known to have contaminated groundwater. Based on their analysis, Happel et al. estimated that 
the minimum number of California UST sites with MTBE present was greater than 10,000. 

Buscheck et al. (1998) evaluated groundwater plume monitoring data from more than 
700 service station sites in four states in different regions of the country. MTBE was detected at 
approximately 83% of the sites, with about 43% of all sites having MTBE concentrations greater 
than 1,000 pg/L. The highest frequencies of detection occurred at sites of currently operating 
stations (n = 466) in Texas and Maryland (96 and 98%), with northern and southern California 
intermediate (83 and 84%), and Florida the lowest (76%). Similar but slightly lower rates of 
occurrence were found at sites with nonoperating stations (n = 243). Concentrations greater than 
1,000 pg/L were found at 55% of the operating sites and 22% of the nonoperating sites. 

The authors suggested that differences in the incidence and levels of MTBE occurrence may have 
been due to factors such as hydrogeologic differences, differing histories of MTBE usage, and 
UST upgrade efforts in the states considered. 

An EPA-supported survey of the 50 states and District of Columbia found that, of the 
34 states that acquire MTBE data from leaking UST sites, 27 (79%) indicated that MTBE was 


14 


present at more than 20% of their sites and 10 (29%) reported MTBE at more than 80% of their 
sites (Hitzig et al., 1998). Interestingly, five states reported detecting MTBE (at >20 pg/L) with 
non-gasoline petroleum such as diesel fuel, jet fuel, and heating oil. The survey also asked about 
contamination of drinking water wells. Of the 49 state programs that responded to the survey, 

25 (51 %) had received reports of private wells contaminated with MTBE. It was estimated that 
the total number of contaminated private wells ranged from 2,256 to 2,663. In addition, 

19 (39%) programs had reports of public drinking water wells contaminated with MTBE, with the 
estimated total number of such wells ranging from 251 to 422. These totals are presented as 
ranges because the survey requested data in ranges (e.g., 1-10, 11-20, etc.) or as highest estimates 
(e.g., estimate if greater than 40). 

The contamination of drinking water wells also was examined by the USGS in an extension 
of the NAWQA study described above (Squillace et ah, 1996). Data were collected in 1995 from 
additional wells in the same 20 NAWQA study units, combined with previously collected data 
from these units, and analyzed for the entire period of 1993-1995 (Zogorski et ah, 1998). 

The data were sorted according to whether or not the sampled wells were used for drinking 
water. This analysis showed MTBE detections in 12 (14%) of 83 urban wells used for drinking 
water and in 19 (2%) of 949 rural wells used for drinking water, with a median concentration of 
approximately 0.50 pg/L. Only one of the more than 1,000 samples exceeded the EPA Drinking 
Water Advisory of 20-40 pg/L. 

The USGS findings for drinking water wells are consistent in certain respects with results 
from a recent study in Maine in which 951 household drinking water wells and 793 Public Water 
Supplies (PWSs) were sampled for MTBE (Maine Department of Human Services, Bureau of 
Health, 1998). At a minimum reporting level of 0.1 pg/L, preliminary results showed MTBE 
detections in 150 (15.8%) of the sampled household wells. The incidence of private well samples 
exceeding state’s maximum contaminant level of 35 pg/L for MTBE was 1.1%, somewhat higher 
than the incidence of such concentrations in the USGS analysis. The Maine report projected that 
approximately 1,400-5,200 private wells across the state could be contaminated at levels 
exceeding 35 pg/L. For the Maine PWSs, 125 (16%) of the samples had detectable levels of 
MTBE, with no samples above the 35 pg/L standard and 48 (6.1%) between 1 pg/L and 35 pg/L. 

In another recent study, the American Water Works Service Company (Siddiqui et al., 

1998) collected data from drinking water wells in 16 states. Forty-four (2%) of 2,120 samples 


15 


from 17 (4%) of 450 wells tested positive for MTBE at a minimum reporting level of 0.2 pg/L, 
with the highest concentration reported at 8.0 pg/L. The detections occurred primarily in eastern 
states in areas with known UST releases. 

Since February 1997, the California Department of Health Services has required public 
water suppliers to monitor their drinking water sources (i.e., ground water and surface water) for 
MTBE. To date, over 4,566 (39%) of 11,837 drinking water sources in California have been 
sampled for MTBE (California Department of Health Services, 1998). Of these, 26 (0.6%) 
sources (18 ground water and 8 surface water) had detectable levels of MTBE, including 
9 sources with samples exceeding California’s drinking water interim action level of 35 pg/L. 
These data are based on a detection limit of 5 pg/L. If all detections are considered, including 
possible false positives below 5 pg/L, 65 sources (1.4%) had detectable levels of MTBE. None 
of the surface water samples exceeded 35 pg/L. 

Other USGS regional studies are ongoing for New England aquifers (Grady, 1997), aquifers 
and surface waters of Long Island, New York and in New Jersey (Stackelberg et al., 1997), and 
fractured bedrock aquifers in Pennsylvania (Lindsey et al., 1997). Also, the USGS and EPA 
entered into a cooperative agreement to conduct a pilot study (managed under the USGS 
National Synthesis Program) in 12 northeastern states to describe the occurrence and distribution 
of MTBE and other VOC’s in drinking water sources through a stratified statistical sampling of 
recent public water supply system data (both ground water and surface water) and ambient 
ground water data (Grady, 1997). 

To require monitoring of drinking water for MTBE or other oxygenates, EPA must first 
promulgate regulations requiring the collection of the data, with monitoring schedules based on 
the size of the public water system. As required by the Safe Drinking Water Act (SDWA), 
amended in 1996 (U.S. Code, 1996), EPA published a drinking water Contaminant Candidate List 
(CCL) on March 2, 1998 (Federal Register, 1998). The CCL is a list of currently unregulated 
contaminants targeted for consideration in priority-setting for the Agency’s drinking water 
program, including regulatory determinations, drinking water research, occurrence monitoring, 
and guidance development such as health advisories. The 1998 CCL identified MTBE as a 
contaminant with specific data gaps in the areas of health effects and occurrence data. These data 
gaps must be filled in order for EPA to make a scientifically informed determination as to whether 
or not MTBE should be regulated with a health-based National Primary Drinking Water 


16 


Regulation. The CCL also serves as a source list of chemicals to evaluate for possible inclusion in 
the Unregulated Contaminant Monitoring Rule (UCMR), required by the SDWA to be finalized 
by August 1999. The proposed UCMR is expected to be published by early 1999 and to include 
MTBE. Contaminants included in the forthcoming rule will be subject to required monitoring by 
the states. Data collected during implementation of the final UCMR will be stored in the National 
Contaminant Occurrence Database (NCOD). The NCOD will provide the basis for identifying 
contaminants for future CCLs, supporting the Administrator’s decisions to regulate contaminants 
in the future, and to assist in reviewing existing regulations and monitoring requirements every six 
years, as required by SDWA. 

The Clean Water Act, Section 305(b) (U.S. Code, 1977) requires states and other 
participating jurisdictions to submit water quality assessment reports to EPA every two years. 
Based on these reports, EPA prepares the National Water Quality Inventory Report to Congress. 
However, a state may or may not provide data on specific unregulated contaminants such as 
MTBE in 305(b) reports, depending on the individual state’s water quality priorities. 

The detection and reporting of oxygenate contamination in water presupposes that adequate 
analytic methods are available for this purpose. The ether oxygenates can be analyzed with 
several standard EPA methods. The most reliable methods use purge-and-trap capillary column 
gas chromatography/mass spectrometry (GC/MS) such as EPA Drinking Water Method 524.2 
(Eichelberger et al., 1992), EPA Waste Water Method 624 (U.S. Environmental Protection 
Agency, 1998b), or EPA Solid Waste (SW-846) Method 8260B (U.S. Environmental Protection 
Agency, 1998c). The USGS GC/MS method SH2020 also has been determined to be reliable for 
ether oxygenates (Connor et al., 1998). These GC/MS methods provide positive identification of 
specific constituents and, as such, they overcome the problem of false identification of coeluting 
constituents. Standard EPA methods that use a GC/photoionization detector (PID) (i.e., Drinking 
Water Method 502.2, Waste Water Method 602, SW-846 Method 8021) also can be useful, but 
because identification with these methods is based on the expected time that a chemical takes to 
pass through the capillary column, false positives are possible from coeluting constituents. 
Depending on the purpose of the analysis (e.g., UST site assessment, drinking water supply 
monitoring), the problem of false identification can be minimized by first determining if MTBE or 
another ether oxygenate is present with a GC/MS method, then performing analyses on additional 
samples with a GC/PID method (Happel et al., 1998). Gas chromatography/flame ionization 


17 



detector (FID) methods can be useful for detection of the alcohols as well as the ether 
oxygenates. However, as with PID, FID is subject to misidentification of coeluting compounds, 
and because FID is sensitive to all organic compounds, detection of specific compounds can be 
more difficult than with other equipment. Despite these problems, a two-dimensional GC/FID 
method for water samples with high hydrocarbon content has been developed using a modified 
ASTM method D4815 (Galperin, 1998). This method has been approved for use in California. 
Both EPA methods 8260B and the modified ASTM method 4815 are capable of detecting TBA 
concurrently with the ether oxygenates, although the detection limit for TBA is significantly 
higher than the detection limits for the ether oxygenates—approximately 30 to 40 pg/L for TBA 
and less than 1 pg/L for the ethers (Rhodes et al., 1998). However, a direct aqueous injection 
GC/MS method (Church et al., 1997) exists for detection of low levels of the ether oxygenates 
and TBA. 

5.2 Needs 

As stated in the Interagency Assessment of Oxygenated Fuels (Interagency Oxygenated 
Fuels Assessment Steering Committee, 1997) and affirmed by the NAS/NRC Review Committee 
(National Research Council, 1996), oxygenates should be added to existing VOC analyte 
schedules and included as routine target analytes for VOCs in drinking water, waste water, 
surface water, ground water, and remediation sites. Monitoring should be long term to support 
trend analyses of possible changes in water quality and the potential for population exposures. 
However, some discretion should be exercised with respect to including oxygenates that have not 
been used or are not expected to be used to any appreciable extent, if by their inclusion the cost of 
such monitoring would be significantly increased. Similarly, any decision to monitor for 
oxygenate transformation products on a widespread basis should be guided by information on the 
occurrence of the respective parent oxygenates and by definitive identification of the respective 
transformation products that would be targeted (see Section 4, Transformation). Given the 
existence of TBA as a primary oxygenate, as a contaminant of MTBE, and as a degradation 
product of MTBE, the inclusion of TBA in ambient ground water quality monitoring programs is 
advisable. It also would be useful to monitor for TBA at specific sites where MTBE 
contamination is known or suspected to have occurred. 


18 


The Interagency Assessment of Oxygenated Fuels (Interagency Oxygenated Fuels 
Assessment Steering Committee, 1997) recommended that a national database for monitoring 
data should be developed cooperatively among relevant governmental and private organizations, 
to be administered by a single federal agency. At present, existing “national” databases appear to 
be limited in their respective scopes. The EPA Safe Drinking Water Information System 
(SDWIS) contains drinking water data from public water supply distribution systems, whereas the 
USGS National Water Inventory System database contains ambient water quality data. 

As specified by the SDWA Amendments of 1996, EPA’s Office of Ground Water and Drinking 
Water is currently developing the first release version (by August 1999) of the NCOD, which will 
expand the existing capabilities of SDWIS. In the longer-term (i.e., 2000 - 2002) the Agency 
plans to upgrade the NCOD to include both public water system and ambient water quality data. 

Assuming that oxygenates are added to VOC analyte monitoring lists, an effort should be 
made after a reasonable period (e.g., 3 to 5 years from now) to analyze these or other databases 
for trends in the occurrence of oxygenates in water. These analyses should be linked to exposure 
assessment efforts (see Section 6, Exposure) and evaluated for guidance as to whether more 
intensive monitoring or other actions are warranted. To the extent possible, monitoring efforts 
and database designs should be undertaken in a manner to relate qualitatively and quantitatively to 
exposure assessments for human populations and aquatic biota. 

The most pressing research need related to analytical methods is to validate existing 
methods for the detection of alcohol oxygenates other than TBA, or develop new cost-effective 
methods for these alcohols. In addition, development of low cost, simple field methods for ether 
oxygenates would be useful. Although field portable GC/PID and GC/FID methods can likely be 
adapted for this purpose, supportive research would be helpful for facilitating their widespread 
use. 


6. EXPOSURE 

6.1 Background 

Based on limited monitoring and occurrence data (see Section 5), a potential for exposure 
of biota and human populations to oxygenates exists. Exposure implies actual contact with a 
contaminant, not just the existence or occurrence of the substance in the environment. Exposure 


19 


characterization requires information on the magnitude and distribution of exposures. Among 
many factors that can affect exposure to oxygenate-contaminated water, unpleasant odor and 
taste have been reported as particularly notable in the case of MTBE in drinking water 
(e.g., Angle, 1991). However, it cannot be assumed that the sensory properties of oxygenates 
would prevent human population exposures to such contaminants. Individuals vary greatly in 
sensory and subjective reactions, and indeed, anecdotal evidence indicates that some individuals 
may have unknowingly consumed drinking water contaminated with MTBE at levels exceeding 
35 pg/L (Maine Department of Human Services, Bureau of Health, 1998). Also, young children 
could be exposed via infant formula and beverages prepared with oxygenate-contaminated water. 
Even if all human exposures to oxygenates could be averted by water treatment processes, 
exposure of biota to contaminated surface or ground water could still occur. 

Taste and odor detection thresholds for MTBE have been reported ranging from 
24 to 135 pg/L for taste and from 15 to 180 pg/L for odor (Malcolm Pirnie, Incorporated, 1998b; 
Dale et al., 1997; Shen et al., 1997; Young et al., 1996; Prah et al., 1994; Vetrano, 1993a,b; 

TRC Environmental Corporation, 1993). Limited testing suggests taste and odor thresholds may 
be somewhat lower for ETBE and TAME than for MTBE (e.g., Shen et al., 1997; TRC 
Environmental Corporation, 1993; Vetrano, 1993a,b). None of the above studies attempted to 
characterize a population distribution of threshold responses. 

It is important to note that detection and recognition thresholds for taste and odor 
sensations are distinct from their hedonic properties, which involve dimensions such as the 
(un)pleasantness and intensity of the sensory experience. The detection threshold is typically 
defined as the concentration at which a subject can detect a taste or odor difference between a 
standard (e.g., “plain” water) and the diluted test substance on a specified percentage (e.g., 50%) 
of the trials. The recognition threshold is the concentration at which a subject can recognize or 
identify the target substance in the diluent. In one study (Dale et al., 1997), four panelists were 
asked to describe the taste and odor of MTBE in odor-free water at concentrations ranging from 
2 pg/L to 190 pg/L. At concentrations of 2 to 5 pg/L, the consensus judgment of the panelists 
was that the taste of MTBE could be described as “sweet.” At concentrations of 21 to 190 pg/L, 
the characterization was either “solvent” or “sweet solvent.” Similar characteristics were 
attributed to the odor of MTBE at concentrations of 21 to 190 pg/L. The panelists also were 
asked to rate the intensity of the taste and odor, which they considered “objectionable” at a 


20 


concentration of approximately 50 pg/L for taste and at approximately 90 to 100 pg/L for odor. 
Note that these tests were conducted with nonchlorinated, odor-free water at 25 °C. 

Chlorination would likely raise the thresholds for the taste and odor of MTBE in water, and 
higher temperatures (e.g., for showering) would likely lower these thresholds. Also, thresholds 
will vary with instruction, training, motivation, age, gender, and other variables that are often not 
controlled for or reported. 

Hedonic responses, along with considerations of consumer cost, convenience, and other 
factors, may figure importantly in the levels of contamination that individuals or communities will 
reject or accept (and consequently be exposed to) in their drinking water. Because cognitive 
factors, including attitudes that may be shaped by information provided through the social milieu, 
can significantly influence sensory perception (Dalton, 1996), populations as well as individuals 
may vary considerably in sensitivity to, and tolerance of, odors and tastes, such that a given 
concentration of contaminant might be quite acceptable to a large majority of persons in one 
group and strongly rejected by an equal proportion in another (cf. Anderson et al., 1995). 

Microenvironmental measurements of VOCs such as benzene and trichloroethylene in 
relation to household water usage (e.g., Lindstrom et al., 1994; Wilkes et al., 1996; McKone and 
Knezovich, 1991) point to the importance of considering multi-media, multi-route personal 
exposures. “Drinking water” is used in many ways besides direct ingestion, including food 
preparation, dish washing, laundering, and bathing. In particular, showering affords a significant 
exposure potential by the inhalation and dermal routes, with variables such as water flow rate and 
temperature influencing exposure levels (Giardino and Andelman, 1996). Although 
physicochemical and other properties of oxygenates differ from VOCs investigated thus far, the 
importance of microenvironmental personal exposures to contaminated household water is 
relevant to oxygenates as well. 

Aquatic, terrestrial, and marine biota are subject to exposure to acute and/or chronic 
releases of fuels and fuel additives. However, very little information exists to characterize 
exposure pathways or exposed ecological receptors in relation to oxygenates (Carlsen et al., 
1997). 


21 


6.2 Needs 


Limited empirical information is available either on the overall distribution of exposures to 
oxygenates in water for the U.S. population as a whole or on “high-end” exposure scenarios 
where oxygenate contamination is already known to occur. One step toward determining the 
prevalence and level of potential exposures to oxygenates would be to obtain monitoring data 
from public water suppliers (see Section 5, Occurrence). However, establishing large-scale 
monitoring programs is probably not the most efficient means for characterizing the potential for 
human population exposures to oxygenates. Rather, statistically representative sampling of public 
and private water supplies, including wells, may afford a more cost-effective approach. 

By coupling such data with qualitative and quantitative data on water usage and consumption 
patterns, it should be possible to model human exposures to specified oxygenates for risk 
assessment purposes (cf. Brown, 1997). The USGS NAWQA program may help address part of 
this need through a stratified statistical sampling of wells across the United States. Also, the 
National Health and Nutrition Examination Survey (NHANES) program may be used to collect 
data on population exposures to oxygenates and their metabolites, by sampling blood and drinking 
water for MTBE and TBA levels. Although the focus of this document is water contamination, 
exposure to oxygenates must ultimately be considered in terms of all relevant pathways and 
routes, including inhalation, ingestion, and dermal contact. 

With respect to locales where oxygenate contamination of the public water supply has 
already been documented, the focus should be on evaluating potential personal exposure scenarios 
involving all household uses of oxygenate-contaminated water (e.g., for drinking, food 
preparation, cleaning, bathing). Several studies of multi-route VOC exposures through showering 
and other uses of tap water (e.g., Weisel and Jo, 1996) provide a substantial foundation for 
modeling as well as empirical studies of oxygenate exposure. As a first step, modeling of personal 
exposures, building on integrative approaches that incorporate macro- and micro-environmental 
pathways and even pharmacokinetic aspects (e.g., Georgopoulos et al., 1997; Piver et al., 1997; 
Rao and Ginsberg, 1997) should be undertaken, using sensitivity analyses to identify areas of 
needed additional data. Although a substantial database already exists for the pharmacokinetics of 
MTBE by inhalation (e.g., Borghoff et al., 1996), additional work is needed to supplement the 
limited pharmacokinetic data for the oral and dermal routes. Biomarkers of exposure 


22 


(e.g., metabolites such as TBA) might warrant investigation if exposures prove to be of sufficient 
concern. 

More extensive data on odor and taste thresholds and hedonic responses to the various 
oxygenates are needed to determine whether or how population exposures may be affected by 
sensory variables. The question of what contaminant levels may be acceptable to different 
consumer populations is not an exposure assessment issue per se, but more data on thresholds and 
hedonic reactions would provide a stronger basis for determining consumer acceptance levels and 
for estimating actual usage of (and thus exposure to) oxygenate-contaminated water. 


7. AQUATIC TOXICITY 

7.1 Background 

The aquatic toxicity of oxygenates has been briefly summarized in the Interagency 
Assessment of Oxygenated Fuels (Interagency Oxygenated Fuels Assessment Steering 
Committee, 1997). Some basic toxicity data exist for MTBE, ETBE, TAME, DIPE, ethanol, and 
TBA for selected aquatic species (e.g., Daphnia magna, Pimephales promelas, Carassius 
auratus). However, EPA has not established water quality criteria for oxygenates for the 
protection of freshwater or marine aquatic life. Currently, testing is underway to evaluate the 
acute and chronic toxicity of MTBE to aquatic organisms (Christensen et al., 1998; Mancini et al., 
1998). Based on the results of this work and other existing data (e.g., Huttenen et al., 1997), the 
EPA Office of Water expects to have a complete data set available for deriving water quality 
criteria for MTBE in early 1999. 

7.2 Needs 

Current actions should provide an appropriate basis for determining whether additional 
effects testing or research is needed. 


23 


8. HEALTH EFFECTS 


8.1 Background 

Most of the testing and research on the toxicity of oxygenates has been concerned with the 
effects of inhaled MTBE in laboratory animals and human volunteers. Little information exists on 
the effects of ingested oxygenates on humans, with the notable exception of the extensive 
database on the health effects of ingested ethanol. However, in the absence of any evidence 
indicating that human populations are exposed to ethanol-contaminated drinking water, the well 
characterized health effects of ingested ethanol need not be considered here. 

A few studies have examined the toxicity of MTBE in laboratory animals via the oral route 
of exposure (Belpoggi et al., 1995; Robinson et al., 1990; IIT Research Institute, 1992; 
Bio-Research Laboratories Limited, 1990). None of these studies used drinking water as a 
medium for administering MTBE to animals; rather, they typically delivered MTBE mixed in olive 
oil or com oil in a bolus dose through a tube into the stomach. This method does not correspond 
very well to the way that drinking water is typically consumed by people. Apart from such 
methodological problems, other questions have been raised about the use of some of these studies 
for risk assessment purposes (cf. National Research Council, 1996; Belpoggi et al., 1998). 
Considerable uncertainty hampers attempts to characterize the health risks related to MTBE in 
drinking water, as illustrated by the absence of a quantitative health risk estimation in a recent 
Drinking Water Advisory on MTBE (U.S. Environmental Protection Agency, 1997) and the 
somewhat divergent conclusions reached by different assessments of the data on MTBE toxicity 
(e.g., International Agency for Research on Cancer, 1998; Froines et al., 1998; California 
Environmental Protection Agency, 1998; European Centre for Ecotoxicology and Toxicology of 
Chemicals, 1997; Interagency Oxygenated Fuels Assessment Steering Committee, 1997). 

Oral toxicity data for other ethers are even more limited, although some work on inhaled 
vapors of ETBE and TAME is currently being conducted under provisions of a Toxic Substances 
Control Act Enforceable Consent Agreement (Federal Register, 1995), and some work has been 
published on the kinetics and toxicity of inhaled ETBE (e.g., Hong et al., 1997; Johanson et al., 
1997; Dorman et al., 1997) and TAME (e.g., Daughtrey and Bird, 1995). TBA is of relevance 
both as a metabolite of MTBE (Borghoff et al., 1996) and as an oxygenate or oxygenate 
by-product. Ingested TBA has been evaluated in rats and mice in a chronic bioassay by the 


24 


National Toxicology Program (Cirvello et al., 1995). Long-term exposure to TBA in drinking 
water produced various toxicologic and carcinogenic effects, including increased incidences of 
kidney and thyroid tumors. 

8.2 Needs 

Given the limitations of information on the oral toxicity of MTBE and the much greater 
database on the inhalation toxicity of MTBE, the question arises as to whether more oral toxicity 
studies should be initiated, or should inhalation toxicity data be extrapolated to estimate oral 
toxicity risk. A significant effort has already been devoted to investigating the kinetic behavior of 
MTBE in rodents with the goal of developing a physiologically based pharmacokinetic (PBPK) 
model to describe the dosimetry of MTBE and TBA in rats and humans (Borghoff et al., 1996). 
This ongoing work is expected to yield a more refined quantitative PBPK model in the near term. 
In addition, a pharmacokinetic study of human volunteers exposed to MTBE by the inhalation, 
oral, and dermal routes is being conducted by the EPA Office of Research and Development. 

As the results of these studies become available, it is anticipated that it will be possible to 
accurately predict levels of MTBE and TBA in rodent and human target organs for different 
routes and levels of exposure to MTBE. Consequently, it should be feasible to use inhalation 
toxicity data from past laboratory animal studies (Bird et al., 1997) to quantitatively estimate oral 
toxicity risks of MTBE in humans. Ultimately, the net health risks from multi-pathway exposures 
to MTBE (e.g., via refueling and motor vehicle use as well as drinking water) need to be assessed. 

The options of initiating further oral toxicity studies or of using PBPK modeling to 
extrapolate from inhalation effects to oral toxicity risk are not mutually exclusive. A study of 
subchronic oral exposure to MTBE would provide better data on the potential for toxic effects as 
well as help validate a PBPK model for cross-route extrapolation. If such an extrapolation is 
unsuccessful, then a new chronic bioassay may be needed to reduce the uncertainties in assessing 
human health risks from chronic exposure to MTBE in drinking water. 

Questions about the human relevance of carcinogenic effects observed in laboratory rodents 
exposed to high concentrations of MTBE also need to be resolved if uncertainties in current 
assessments of human cancer risk are to be reduced. In view of the weight necessarily attached to 
the cancer bioassays on MTBE, it would be desirable to reexamine and confirm the pathology 
data from all of these studies. Alternative assays for carcinogenicity, such as transgenic mice 


25 


(Tennant et al., 1995) and medaka fish (Boorman et al., 1997) assays, may offer relatively rapid 
approaches for collecting additional data that could contribute to a weight-of-evidence 
determination as well as insights on the modes of action. Although the latter approaches are 
unlikely to provide dose-response information that would enhance quantitative potency estimation 
(a critical need), and interpretation of negative results from these assays could be problematic, 
they could provide supporting or confirmative evidence of certain tumor types and thus assist in 
interpreting the relevance of inhalation effects for drinking water exposure. 

The database for TBA may be adequate to characterize the oral toxicity of TBA. Given the 
potential for human exposure to TBA either as a metabolite, as an oxygenate itself, or as a natural 
biodegradation product of MTBE in ground water, an assessment of the carcinogenic and 
noncarcinogenic health risks of TBA should be undertaken. 

The best strategy for the other ethers may be to obtain pharmacokinetic data (for some, 
work is already underway or anticipated for the inhalation route [U.S. Environmental Protection 
Agency, 1998d]) and take such information into account in designing and conducting oral toxicity 
testing of these ethers. This strategy is predicated on low usage of ethers other than MTBE. 

If occurrence or exposure data become available and suggest otherwise, the need for more 
intensive investigation of the pharmacokinetics and health effects of other ethers may be elevated. 
As for degradation products of oxygenates (other than TBA), more information on the occurrence 
and concentrations of these chemicals is needed to guide decision-making about which chemicals 
to test. 


9. RELEASE PREVENTION 

9.1 Background 

Although the contribution of point source releases to the problem of environmental 
contamination from fuel oxygenates cannot be quantitatively characterized at present, such 
releases are clearly a matter of risk management concern. The compatibility of fuel storage and 
distribution system components with the fuel they contain has always been an issue for system 
component manufacturers, petroleum refiners and distributors, and regulators. Federal 
regulations (§280.32, Code of Federal Regulations, 1990) require that UST system components 


26 


be compatible with the constituents they contain. The changing composition of gasoline, 
particularly with the addition of ethers and alcohols, has raised the question of whether all existing 
systems are compatible with newer fuels and fuel additives. 

Steel tanks and piping are not thought to be significantly corroded by oxygenates (Douthit 
and Davis, 1988; Geyer, 1995), but the effects of oxygenates on fiberglass reinforced plastic 
(FRP) tanks and piping have been less clear. Although MTBE and other fuel ethers have been 
shown not to cause corrosion of FRP (Douthit et al., 1988; Drake et ah, 1995), manufacturers 
such as Owens-Coming (Bartlow, 1995) have indicated that they do not extend their 30-year 
warranties to older (pre-1984) FRP tanks exposed to alcohols, depending on the type and 
concentration of the alcohol used. No known published research has examined older tanks 
exposed to up to 10% ethanol. 

The possibility exists that some UST system components, such as FRP tanks and piping and 
flexible piping, may be permeable to MTBE and other oxygenates. Such permeability might 
account for cases of MTBE contamination at gasoline stations where no leak could be detected 
and no other gasoline constituents were found. However, some doubt exists that the relatively 
large molecular weight of MTBE would allow it to pass through FRP (Curran, 1997). The only 
known study of FRP permeability to fuel oxygenates evaluated gasoline with 10 percent ethanol 
and found no liquid gasoline loss after 31 days (Smith Fiberglass Products Inc., 1996). No known 
work has been conducted on FRP permeability to any other oxygenate. 

Elastomer seals, used for gaskets and o-rings throughout UST systems and petroleum 
pipelines, may have compatibility problems with oxygenated fuels. An American Petroleum 
Institute (1994) survey indicated that petroleum pipeline and terminal managers had noticed 
significant deterioration of many different types of elastomers associated with fuel oxygenates. 

The study, however, did not discuss the specific types of oxygenates that caused specific 
problems, nor did it discuss the concentrations of the oxygenates. Many of the problems listed 
were likely caused by “neat” (pure) solutions of the oxygenates, but the study raises the concern 
that more dilute solutions could cause problems as well. 

Another study (Alexander et al., 1994) tested six elastomers in various concentrations of 
MTBE, ETBE, TAME, ethanol, and methanol. The authors found that although three of the seals 
were not able to withstand neat MTBE, all of the seals were acceptable for use in solutions of all 
five oxygenates when concentrations were less than 20% (immersed for 168 hours at 23 °C). 


27 


Hotaling (1995) tested 15 elastomers at 46 °C for 6 months and found significant deterioration of 
three types of elastomers when exposed to concentrations of only 5% MTBE in gasoline. As a 
result, Hotaling found that these seals may be unsuitable for even low percentages of MTBE.” 
In actual use, however, EPA is not aware of any reports of UST system elastomers failing and 
causing a release because of exposure to gasoline containing oxygenates. 

In addition to liquid-phase oxygenates, compatibility with vapor phase oxygenates also 
should be considered. Because the vapor pressure of MTBE is much higher than many other 
gasoline constituents, gasoline vapors should theoretically have much higher concentrations of 
MTBE than are found in the liquid phase (Davidson, 1998). These vapors would occur in the 
headspace of tanks and vapor recovery systems. In addition, liquid-phase MTBE-enriched 
condensate could form inside these vapor recovery systems. Hotaling (1995) tested elastomers 
exposed to MTBE vapors and found significant deterioration to some elastomers throughout the 
concentration ranges tested (5 to 100%). 

Dispenser sumps, used to catch small amounts of fuel below gasoline dispensers, are 
typically made of high density polyethylene. Although these sumps should be checked 
periodically to remove any fuel, it is possible that some measurable quantities of gasoline and 
oxygenates could be released via the sumps. Another potential concern is tank liners. These are 
plastic tanks within tanks, typically used inside steel tanks that may have started to corrode, and 
are used to avoid replacing the original tank. Certain liner materials may not be compatible with 
oxygenated fuels (Meli, 1996). 

Some information suggests that leak detection systems may not be mitigating UST releases 
as much as might be desired. In a survey of UST leak cases in California (Farahnak and Drewry, 
1997), 263 (84%) of 313 cases were discovered in the course of tank closure activities; 15 (<5%) 
of the cases were identified through leak detection methods. For 132 cases with available 
monitoring data, the average lag between the date of last monitoring and discovery of a leak was 
29 months. No information was provided regarding the presence of oxygenates in the survey. 
Although the survey did not resolve whether problems were due to the systems, misuse or a lack 
of use of them, or a combination of these factors, the report highlights the importance of leak 
detection issues, which in turn are clearly relevant to addressing oxygenated fuel releases. 


28 


9.2 Needs 


The issue of materials compatibility with oxygenated fuels may prove to be quite 
manageable. However, a number of unanswered questions need to be resolved to ensure that 
releases do not and will not occur. It is important to characterize fully the effects of ethers and 
alcohols on elastomers, FRP, and other components of pipelines and tanks, particularly after 
several years of aging. The potential for leakage is unknown for older (pre-1984) FRP tanks that 
may be exposed to high (e.g., 10%) concentrations of ethanol. Also, the possible permeability of 
MTBE through FRP tanks and piping or flexible piping cannot be ruled out with existing data. 
Additional research is needed to resolve contradictory findings on the compatibility of elastomer 
seals with MTBE. Vapor recovery systems need to be examined more closely in terms of 
compatibility with concentrated MTBE vapor. Dispenser sumps need to be evaluated to 
determine if they are a potentially significant source of releases. Independent research is needed 
on the compatibility of currently marketed tank liners with ethanol. 

Although newer technologies and regulations are intended to reduce the problem of leaking 
UST systems for conventional fuels, the different chemical properties of the various oxygenated 
fuels raise questions not only about the compatibility of existing systems but also about leak 
detection methodologies. Even though the differences in the physicochemical properties of 
oxygenated and non-oxygenated fuels may be small, modest research efforts may be required to 
reevaluate and confirm the performance and accuracy of in-tank and external leak detection and 
monitoring technologies. 

Based upon the results of the above studies, new and improved approaches and technologies 
could be developed to repair or replace problem areas and to prevent future problems through the 
use of more advanced materials and design concepts. 


10. CONTAMINANT REMOVAL 

10.1 Background 

Various methods are available for removing contaminants from soils, ground water, waste 
water, and drinking water. Many of these techniques are potentially applicable to contamination 
from oxygenates. However, very limited information exists on the technical feasibility and costs 


29 


of implementing them for oxygenate removal under field-scale operating conditions. 

The following background discussion is not meant to differentiate these processes in their 
applications, but rather to address their general efficiency for soils or waters contaminated with 
MTBE or other oxygenates. The discussion also notes those technologies that may be 
appropriate for in situ subsurface remediation, those that may be more applicable to above ground 
treatment of contaminated ground water, and those that may be more suitable for drinking water 
treatment at the wellhead or in a drinking water treatment plant. 

Water treatment to remove MTBE and other oxygenates will frequently be conducted as 
part of an overall treatment process to remove other contaminants such as benzene. 

Consequently, it is worthwhile to ask if an ongoing treatment process also will be effective for 
oxygenate removal. However, because oxygenates have different physical and chemical 
properties, a technology suitable for one oxygenate may not be suitable for another. 

Subsurface treatment methods are often classified as those that transform, immobilize, or fix 
the contaminants in situ, and those that extract the contaminant from the subsurface for ex situ 
treatment on the surface. Both types are potentially applicable to MTBE and other oxygenates. 

In situ biological treatment is known to be effective for the BTEX component of fuels, but its 
effectiveness for oxygenates is subject to debate. The feasibility of an in situ bioremediation 
process depends on many factors, including the biodegradation rate, the redox conditions, and the 
presence of other contaminants. Information is very limited on the field application of in situ 
bioremediation to oxygenates either as part of an active treatment process or for natural 
attenuation. 

Soil vapor extraction (SVE) is commonly used to remove gasoline contaminants from the 
unsaturated zone at spill sites. Based on its high vapor pressure and low affinity for organic 
carbon in soil, MTBE would be expected to be readily removed from soil by vapor extraction. 

A computer model, VENT2D, has been used to simulate this process for a gasoline-MTBE 
mixture (Conrad and Deever, 1995). In this simulation, MTBE showed the highest rate of mass 
loss of five gasoline components, as would be predicted based on their relative vapor pressures. 
Hence, MTBE and other ethers with high vapor pressures are not expected to be problematic for 
this technology. Grady and Johnson (1995) empirically demonstrated that SVE was successful in 
recovering MTBE, and as expected, the recovery of MTBE was greater than the recoveries for 
BTEX compounds. 


30 


Low-temperature thermal desorption (LTTD) is an ex situ soil treatment technology that 
uses temperatures below ignition levels to separate volatile contaminants from soil. Due to the 
high vapor pressure of MTBE, LTTD should be very effective in removing MTBE from soil. 
However, because MTBE separates from gasoline and dissolves quickly in water, both SVE and 
LTTD must be used soon after a release; otherwise most of the MTBE may have already moved 
from the soil into the ground water. 

Air sparging involves the injection of air below the water table. The mechanisms for 
removal are stripping and potentially oxygen-enhanced biodegradation. Bass (1996) found that 
air sparging removed MTBE from ground water, with down-gradient wells showing 99% removal 
of MTBE. Levels continued to decline for 13 months after the air sparging unit was shut off, 
presumably due to aerobic degradation. Similar results also were reported by Cho et al. (1997). 

Because MTBE does not adsorb well to soil and is highly soluble in water, “pump and treat” 
technology (i.e., pumping contaminated ground water and treating it above ground) may be 
effective in conjunction with certain above-ground biological or physical/chemical 
contaminant-removal processes. Conditions such as the presence of complex hydrogeology that 
create “dead” zones that are isolated from zones of high hydraulic conductivity will reduce the 
effectiveness of pump and treat for MTBE, despite its favorable chemical and physical 
characteristics. 

Studies have indicated that MTBE can biodegrade in ex situ biological treatment systems 
under aerobic and anaerobic conditions (see Section 4, Transformation). Once the conditions for 
biodegradation of oxygenates are fully defined, field work can be completed to determine the 
practicality of ex situ biological treatment for oxygenates removal. 

Granular activated carbon (GAC) adsorption is a frequently used treatment process for 
organic contaminants. However, because of its limited adsorption capacity for MTBE, GAC is 
generally not cost effective for removing MTBE (Speth and Miltner, 1990). Therefore, it is not 
expected that adsorption would be generally used for removing MTBE on a large scale. This is 
especially true at high influent concentrations that would limit the time that a GAC column could 
be effective. For public water supplies, field studies have shown that carbon adsorption is not 
cost effective for MTBE removal unless the concentrations are very low (McKinnon and Dyksen, 
1984). For example, even with an influent concentration of 30 pg/L, the carbon beds need to be 
regenerated frequently. Other ether oxygenates have slightly lower solubilities than MTBE and 


31 


thus would be more effectively adsorbed. However, alcohol oxygenates such as ethanol and TBA 
are infinitely soluble, and thus adsorption would be ineffective for these compounds. Carbon 
adsorption may be useful as a polishing step to air stripping. 

Malley et al. (1993) have shown that MTBE adsorbs more strongly to synthetic adsorbents 
than to GAC. Because the capital cost of the synthetic adsorbents was much higher than that of 
GAC, the authors concluded that synthetic adsorbent removal of MTBE was not economically 
feasible. However, synthetic adsorbents could be economically feasible for oxygenate removal if 
an inexpensive in situ regeneration process such as steam could be used (Malley et al., 1993). 

For volatile organic compounds, air stripping is a cost effective alternative. However, the 
Henry’s Law constant for MTBE is low (see Appendix 1), indicating a relatively low efficiency 
for air stripping. Air stripping at a very high air-to-water ratio (e.g., 200:1) has been found 
effective in removing 93 to 99% of MTBE from ground water (McKinnon and Dyksen, 1984; 
American Petroleum Institute, 1990), but at air-to-water ratios of 44:1, 75:1, and 125:1 the 
percentage of MTBE removed was 44, 51, and 61%, respectively (McKinnon and Dyksen, 1984). 
By comparison, an effective air-to-water ratio for benzene is typically near 50:1. High air-to- 
water ratios can lead to severe operating problems such as scaling and freezing during cold 
weather operations. McKinnon and Dyksen (1984) found that the cost of air stripping treatment 
was approximately 55% of that for carbon treatment. However, the off gas of the air stripping 
unit was not treated. Treating the off-gas stream would approximately double the cost of the air 
stripping system. Air stripping followed by GAC adsorption was found to be very effective for 
MTBE removal in this study, as also was found by Truong and Parmele (1992). Other 
oxygenates such as ETBE, TAME, and DIPE have higher Henry’s Law constants than MTBE 
(approximately 3 to 20 times higher), indicating that air stripping would be at least slightly more 
effective for them. For example, in the study by McKinnon and Dyksen (1984) the percentage 
removal of DIPE at an air-to-water ratio of 200:1 was greater than 99% (McKinnon and Dyksen, 
1984). However, alcohol oxygenates have very low Henry’s Law constants, indicating that air 
stripping would not be effective for these compounds. 

Yeh (1992) found that hydrogen peroxide in the presence of iron (Fenton’s reaction) 
degraded ETBE and MTBE. This was later confirmed under laboratory conditions by Chen et al. 
(1998) and other researchers. Therefore, the hydroxyl radicals produced by Fenton’s reaction 
appear to be an effective treatment agent. Ozone/ultraviolet (UV), ozone/peroxide, UV/peroxide, 


32 


and ozone/sonication also have potential as treatment technologies for oxygenate destruction. 

The American Petroleum Institute (1991) reported that advanced oxidation is more cost effective 
than other zero emission technologies such as steam stripping, ex situ biological oxidation, and air 
stripping with off-gas control. Malcolm Pimie Incorporated (1997) also concluded that advanced 
oxidation is more cost-effective than carbon adsorption or air stripping with off-gas control. 
Malley et al. (1993) reported over 95% removal of MTBE using UV/peroxide. Oxidation 
byproducts included methanol, formaldehyde, and 1,1-dimethylethyl formate. Using UV/peroxide 
with a highly contaminated ground water produced less removal (up to 83%) presumably due to 
the effects of alkalinity scavenging of hydroxyl radicals and competition from other organics 
(Malley et al., 1993). The American Petroleum Institute (1997) reported up to 98% removal of 
MTBE in a UV/peroxide reactor under various conditions. Diisopropyl ether had higher removal 
rates than MTBE, indicating that DIPE is more easily destroyed by hydroxyl radicals than MTBE. 
Compared to benzene, MTBE is only moderately reactive, with reaction rate constants seven 
times lower than that for benzene. Kang and Hoffmann (1998) found that the combination of 
ozonation and sonication can effectively degrade MTBE into tert-butyl formate, TBA, methyl 
acetate, and acetone. Leitner et al. (1994) found that ozone/hydrogen peroxide treatment could 
eliminate ETBE and MTBE, with ETBE more reactive than MTBE. The ozonation byproducts 
were tertiary butyl formate, tertiary butyl acetate, and TBA. 

Because advanced oxidation systems increase the biodegradability of the organic matter in 
the water, biofiltration may be recommended following oxidation to control for biogrowth in 
drinking-water distribution systems. The result could be an effective two-stage process: abiotic 
oxidation followed by aerobic biodegradation of the oxygenates. 

10.2 Needs 

Numerous areas of contaminant-removal research are needed for MTBE and other 
oxygenates. Because remediation and drinking water sites often differ with regard to contaminant 
concentration, clean-up goals, secondary-effect issues such as biological regrowth and corrosion, 
and public acceptability, this section is separated into remediation and drinking-water subsections. 
For both subsections, comparative cost estimates for all technologies are needed. 

The research needs for the removal of oxygenates from waste water are not discussed 
separately here. Although waste waters typically contain higher levels of background organics 


33 


and inorganics that might interfere with the removal of oxygenates, it is not clear that oxygenate 
contamination of waste water is a widespread occurrence. To the extent that biological 
treatments (e.g., activated sludge, trickling filters) that are commonly practiced for wastewater 
streams may be effective in removing oxygenates by virtue of the biodegradation and stripping 
mechanisms within these technologies, many of the research needs discussed below will be 
pertinent to the removal of oxygenates from waste water. This is especially true of biological 
degradation, extensively covered in Section 4 (Transformation). 

10.2.1 Remediation Needs 

Remediation research is needed for both in situ remediation and ex situ cleanup of extracted 
ground water. This research should build on and expand earlier and ongoing work on remediation 
of ground water contaminated by other organic compounds. Research is likely to be most 
productive if it focuses initially on evaluating the applicability of known remediation technologies 
and adapting them to remediation of MTBE and other oxygenates. Cost as well as technical 
feasibility should be examined. 

There is a pressing need for data on biodegradation (see Section 4, Transformation). 

Optimal conditions for biodegradation processes for in situ and ex situ contaminant removal need 
to be determined. This information is needed both to develop enhanced bioremediation 
technologies and to better understand the applicability of natural attenuation and risk based 
corrective action at UST sites with oxygenate contamination. A particular focus should be on the 
introduction of oxygen and nutrients for in situ plume treatment and the potential for abiotic 
oxidation and aerobic biodegradation in porous-reactor barriers. Data are needed from field 
research and supporting laboratory studies under a variety of conditions, including different 
geochemical conditions, presence of other contaminants, and oxygenate concentrations. 
Information gathered from research regarding optimal biological conditions for oxygenate 
removal may lead to cost-effective remediation processes. Research on in situ abiotic oxidation is 
a lower priority. 

Extraction processes, including pump and treat, SVE, LTTD, in-well stripping, dual-phase 
extraction, and air sparging, need to be further evaluated. Specifically, the optimal operating 
conditions, effectiveness, and costs of these processes should be investigated for MTBE and other 
oxygenates. Also, off-gas control for SVE, air sparging, in-well extraction, and LTTD need to be 


34 


addressed when appropriate. Finally, the effect of temperature on Henry’s Law constants for the 
entire class of oxygenates should be studied. 

There is a particular need for research to develop and evaluate both biotic and abiotic 
surface treatment systems for extracted ground water. Air stripping is known to work, but many 
locations may require off-gas treatment. Research is needed to determine the effectiveness and 
cost of off-gas control. Promising research on bioreactors should be continued. For ex situ 
abiotic oxidation, Fenton’s reagent, ozone/UV, ozone/peroxide, UV/peroxide, and 
ozone/sonication need to be further evaluated in terms of efficiency and cost under a variety of 
operating conditions. By-products of oxygenate degradation should be identified under different 
conditions. By-product destruction also may need to be evaluated. These oxidative processes 
should be optimized so that a site demonstration can be conducted to determine their cost 
effectiveness. GAC is not likely to be cost effective as an ex situ treatment process for MTBE in 
water but may have applicability to situations with low flow and low concentrations. 

Sorbents such as vermiculite, straw, and peat have been proposed for oxygenate removal. 
Although their low cost may offset their low adsorption capacities, this is a low priority research 
area and should be limited to gathering and evaluating existing information at this time. 

10.2.2 Drinking-Water Treatment Needs 

Drinking-water treatment research needs to focus on low concentrations of contaminants 
typically found in source waters. Consideration should be given to the scale of water treatment; 
from large drinking water plants that treat hundreds of millions of liters a day to point-of-use 
systems that treat liters per day. Two technologies that should be investigated first include air 
stripping and hydroxyl-radical processes. For air-stripping, a matrix of the effectiveness and cost 
needs to be completed for various conditions (e.g., with and without off-gas control), which 
would allow more direct comparison to other treatment technologies. Also, configurations other 
than packed-tower aerators should be evaluated. Finally, the effect of temperature on Henry’s 
Law constants for the entire class of oxygenates needs to be thoroughly studied so as to aid in the 
design and evaluation of heated air stripping and steam stripping systems. 

For abiotic oxidation processes, a hydroxyl radical treatment, Fenton’s reagent, has been 
shown to be effective for MTBE. Because of secondary effects, it is unlikely that Fenton’s 
reagent would be used in a drinking water facility. However, other hydroxyl radical processes 


35 


that utilities have experience with, such as ozone/peroxide, ozone/UV, and peroxide/UV, need to 
be more extensively evaluated. Also, the applicability of the ozone/sonication process for 
drinking water treatment needs to be evaluated, including evaluation of UV lamp technologies. 
Oxidation byproducts, including bromate, should be identified and quantified under different 
conditions and byproduct destruction also may need to be evaluated. These oxidative processes 
need to be optimized so that a site demonstration can be conducted to determine their relative 
cost effectiveness. 

Also, as previously mentioned, oxidation processes have been shown to increase the 
biodegradability of natural organics in water. Therefore, biofilters may be used in drinking water 
facilities to control distribution-system regrowth. The removal of oxygenates and oxygenate 
degradates or byproducts in these biofilters should be studied. Limited data exist for 
biodegradation under drinking-water conditions, but the increase in biodegradability of natural 
organics due to hydroxyl-radical treatment potentially holds promise for the removal of 
oxygenates and their degradates as a secondary substrate, even at low concentrations. Drinking 
water biodegradation work must concentrate on removing low levels of oxygenates. 

Other biofiltration processes that utilize the addition of primary substrates should not be 
conducted under the auspices of drinking water treatment research. Primary substrates added to 
drinking water treatment streams are potentially problematic for several reasons: the primary 
substrate could contribute to deleterious human health effects; the primary substrate or its 
degradation byproducts might serve as disinfection byproduct precursor material; biogrowth 
might occur in the distribution system; and public dissatisfaction might result for these and other 
reasons. 

Other drinking-water contaminant removal processes that need to be evaluated include 
GAC, carbonaceous adsorbents, and new bioreactor membrane technologies. For GAC, work 
needs to be completed in developing a matrix of the effectiveness and cost under various 
conditions. Because of its expected poor removal of oxygenates, GAC should be evaluated as a 
polishing step for air stripping technologies or as a biologically-active filter. Desorption from 
GAC also should be studied. 

Synthetic carbonaceous adsorbents are very effective in removing many types of organic 
compounds from water. In general, steam is very effective for reversing adsorption processes for 


36 


weakly adsorbing contaminants such as MTBE. Therefore, a study of an automated system that 
would adsorb oxygenates then desorb (regenerate) under steam conditions should be initiated. 

An automated reverse osmosis system may be applicable for small utilities (under 
500,000 gal/day). However, the potential for success for reverse osmosis is limited due to the 
low molecular weights (32 to 102 Daltons) of most oxygenates, and thus only a quick, low-cost 
evaluation of this process is warranted. Other membrane devices such as carbon-fiber bioreactor 
membranes may be more effective; however, preliminary information is needed before extensive 
research is conducted. 


11. CONCLUSIONS 

The following priorities emerge from the foregoing discussion. No attempt is made to rank 
these needs relative to each other because they are all critical and are independent of each other in 
certain respects. For example, even though more information on biodegradation would assist in 
the development of contaminant removal methods, it does not follow that needed work on 
contaminant removal methods should be deferred to biodegradation studies. It is reasonable to 
expect that efforts can proceed concurrently in each of the areas identified here. It is also 
recognized that different organizations may rank priorities differently, depending on their mission, 
mandates, programmatic objectives, funding constraints, and other factors. For this reason, 
priority ranking of the following needs may vary among organizations, but all of them are valid 
and important. Therefore, each of the following needs should be given priority consideration. 

• Determination of the relative contributions of point and non-point sources of oxygenate fluxes 
to surface and ground waters. 

• Determination of oxygenate biodegradation rates and pathways under representative 
geochemical conditions, and identification of degradation by-products and their environmental 
fate. 

• Inclusion of oxygenate analytes and principal suspected transformation products wherever VOC 
monitoring of water is routinely performed. 

• Statistically representative sampling of public and private water supplies and modeling of 
multi-media, multi-pathway personal exposures for estimating population distributions of 


37 


exposures; modeling and empirical studies of “high-end” microenvironmental exposure 
scenarios. 

• Completion of PBPK modeling and cancer mechanistic studies to enhance confidence in 
extrapolating from laboratory animal inhalation toxicity data as a basis for estimating oral 
toxicity risk of MTBE for humans; subchronic oral toxicity study of MTBE in drinking water. 

• More extensive evaluation of oxygenate effects on materials used in tanks and pipelines, 
especially after aging over a period of years. 

• Evaluation of the relative cost-effectiveness of candidate technologies for removing oxygenate 
contaminants from water under various conditions, with iterative efforts to optimize the most 
promising technologies, develop new innovative approaches, and evaluate the comparative cost 
effectiveness of available technologies. 

• Updating of risk characterizations as results of the above work become available. 

Efforts to address the issues identified in this document have been underway for some time, 
and new efforts are continually being initiated. Consequently, it is very difficult to describe the 
current state of the science in an accurate, up-to-date manner. Appendix 2 contains a listing of 
current projects related to oxygenates in water. The descriptions of projects are not adequate to 
convey the extent of work being undertaken; the intent is to provide an impression of the scope of 
studies underway and information to assist readers if they wish to obtain more details about any 
particular project. 

The purpose of conducting the work identified in this document is to provide a better basis 
for characterizing the potential health and environmental risks of oxygenates and for informing 
risk management and policy decision making. Risk assessment and risk management efforts 
directed at oxygenates in water have been occurring and will likely continue. If the environment 
and public health are to be protected effectively and efficiently, however, adequate scientific 
information and technical data are essential. 


38 


REFERENCES 


Alexander, J. E.; Ferber, E. P.; Stahl, W. M. (1994) Avoid leaks from reformulated fuels: choose an elastomeric 
sealing material according to the type and concentration of oxygenate (ether and/or alcohol) added to the 
fuel. Fuel Reformulation 4(Mar/Apr): 42-46. 

American Petroleum Institute. (1990) A compilation of field-collected cost and treatment effectiveness data for the 
removal of dissolved gasoline components from groundwater. Washington, DC: American Petroleum 
Institute; API publication 4525. 

American Petroleum Institute. (1991) Cost-effective, alternative treatment technologies for reducing the 

concentrations of methyl tertiary butyl ether and methanol in groundwater. Washington, DC: American 
Petroleum Institute; API publication 4497. 

American Petroleum Institute. (1994) Effects of oxygenated fuels and reformulated diesel fuels on elastomers and 
polymers in pipeline/terminal components. Washington, DC: American Petroleum Institute; API publication 
1132. 

American Petroleum Institute. (1997) Field evaluation of biological and nonbiological treatment technologies to 
remove MTBE/oxygenates from petroleum product terminal wastewaters. Washington, DC: American 
Petroleum Institute; API publication 4655. 

Anderson, H. A.; Hanrahan, L.; Goldring, J.; Delaney, B. (1995) An investigation of health concerns attributed to 
reformulated gasoline use in southeastern Wisconsin: phase 1, random digit dial telephone survey, final 
report. Madison, WI: Wisconsin Department of Health and Social Services, Division of Health, Bureau of 
Public Health; May 30. 

Angle, C. R. (1991) If the tap water smells foul, think MTBE [letter]. JAMA J. Am. Med. Assoc. 266: 2985-2986. 

Baehr, A. L.; Ayers, M. A. (1997) Occurrence and movement of contaminants through the urban hydrologic 
cycle—FY97 workplan update [for NAWQA Comprehensive Urban Study]. West Trenton, NJ: U.S. 
Geological Survey, Long Island-New Jersey National Water-Quality Assessment Program; February 1. 

Baehr, A. L.; Stackelberg, P. E.; Baker, R. J.; Kauffman, L. J.; Hopple, J. A; Ayers, M. A. (1997) Design of a 

sampling network to determine the occurrence and movement of methyl tert-butyl ether and other organic 
compounds through the urban hydrologic cycle. In: American Chemical Society Division of Environmental 
Chemistry preprints of papers, 213th. San Francisco, CA: American Chemical Society; v. 37: 400-401. 

Bartlow, D. (1995) [Letter to Owens-Coming tank customers clarifying the use of fiberglass underground storage 
tanks produced by Owens-Coming for the storage of ether and alcohol fuel blends]. Toledo, OH: 
Owens-Coming World Headquarters; April 14. 

Bass, D. H. (1996) Performance of air sparging systems: a review of case studies [unpublished presentation notes]. 
Norwood, MA: Groundwater Technology, Inc. 

Belpoggi, F.; Soffritti, M.; Maltoni, C. (1995) Methyl-tertiary-butyl ether (MTBE)—a gasoline additive—causes 
testicular and lymphohaematopoeitic cancers in rats. Toxicol. Ind. Health 11: 119-149. 

Belpoggi, F.; Soffritti, M.; Maltoni, C. (1998) Pathological characterization of testicular tumours and 
lymphomas-leukaemias, and of their precursors observed in Sprague-Dawley rats exposed to 
methyl-tertiary-butyl-ether (MTBE). Eur. J. Oncol. 3: 201-206. 


39 


Bio-Research Laboratories Limited. (1990) Mass balance of radioactivity and metabolism of methyl ferf-butyl ether 
(MTBE) in male and female Fischer 344 rats after intravenous, oral and dermal administration of 
14 C-MTBE. Senneville, Quebec, Canada: Bio-Research Laboratories Ltd.; report no. 38843. 

Bird, M. G.; Burleigh-Flayer, H. D.; Chun, J. S.; Douglas, J. F.; Kneiss, J. J.; Andrews, L. S. (1997) Oncogenicity 
studies of inhaled methyl tertiary-butyl ether (MTBE) in CD-I mice and F-344 rats. J. Appl. Toxicol. 
17(suppl. 1): S45-S55. 

Boorman, G. A.; Botts, S.; Bunton, T. E.; Foumie, J. W.; Harshbarger, J. C.; Hawkins, W. E.; Hinton, D. E.; 
Jokinen, M. P.; Okihiro, M. S.; Wolfe, M. J. (1997) Diagnostic criteria for degenerative, inflammatory, 
proliferative nonneoplastic and neoplastic liver lesions in medaka (Oryzias latipes ): consensus of a National 
Toxicology Program Pathology Working Group. Toxicol. Pathol. 25: 202-210. 

Borden, R. C.; Daniel, R. A.; LeBrun, L. E., IV; Davis, C. W. (1997) Intrinsic biodegradation of MTBE and BTEX 
in a gasoline-contaminated aquifer. Water Resour. Res. 33: 1105-1115. 

Borghoff, S. J.; Murphy, J. E.; Medinsky, M. A. (1996) Development of a physiologically based pharmacokinetic 
model for methyl tertiary -butyl ether and tertiary -butanol in male Fischer-344 rats. Fundam. Appl. Toxicol. 
30: 264-275. 

Brown, S. L. (1997) Atmospheric and potable water exposures to methyl fe/t-butyl ether (MTBE). Regul. Toxicol. 
Pharmacol. 25: 256-276. 

Buscheck, T. E.; Gallagher, D. J.; Kuehne, D. L.; Zuspan, C. R. (1998) Occurrence and behavior of MTBE in 
groundwater. Presented at: Underground storage tank conference: '98 & beyond; April; Los Angeles, CA. 
Sacramento, CA: State of California Water Resources Control Board. 

California Department of Health Services. (1998) Summary of sampling of public drinking water systems for 

methyl tertiary butyl ether (MTBE). Sacramento, CA: Prevention Services, Division of Drinking Water and 
Environmental Management; November 23. Available online at: 
www.dhs.cahwnet.gov/org/ps/ddwem/chemicals/MTBE/mtbesummary.htm. 

California Environmental Protection Agency. (1998) Evidence on the carcinogenicity of methyl tertiary butyl ether 
(MTBE) [draft]. Sacramento, CA: Office of Environmental Health Hazard Assessment. Available online at: 
http://www.oehha.org/docs/Dmtbcmr.htm. 

Carlsen, T.; Hall, L.; Rice, D. (1997) Ecological hazards of MTBE exposure: a research agenda. Springfield, VA: 
U.S. Department of Commerce, National Technical Information Service; report no. UCRL-ID-126290. 

Chen, C. T.; Tafuri, A. N.; Rahman, M.; Foerst, M. B. (1998) Chemical oxidation treatment of petroleum 
contaminated soil using Fenton's reagent. J. Environ. Sci. Health A33: 987-1008. 

Cho, J. S.; Wilson, J. T.; DiGiulio, D. C.; Vardy, J. A.; Choi, W. (1997) Implementation of natural attenuation at a 
JP-4 jet fuel release after active remediation. Biodegradation 8: 265-273. 

Christensen, K. P.; Hockett, J. R.; Stubblefield, W. A.; Steen, A.; Grindstaff, J.; Wong, D. C. L.; Arnold, W. R. 
(1998) Derivation of ambient water quality criteria for MTBE: toxicity to selected freshwater organisms. 
Presented at: The natural connection: environmental integrity and human health. SETAC 19th annual 
meeting, poster session; November; Charlotte, NC. Pensacola, FL: Society of Environmental Toxicology and 
Chemistry; PHA148. 

Church, C. D.; Isabelle, L. M.; Pankow, J. F.; Rose, D. L.; Tratnyek, P. G. (1997) Method for determination of 
methyl tert -butyl ether and its degradation products in water. Environ. Sci. Technol. 31: 3723-3726. 


40 


Cirvello, J. D.; Radovsky, A.; Heath, J. E.; Famell, D. R.; Lindamood, C., III. (1995) Toxicity and carcinogenicity 
of f-butyl alcohol in rats and mice following chronic exposure in drinking water. Toxicol. Ind. Health 
11: 151-165. 

Code of Federal Regulations. (1990) Technical standards and corrective action requirements for owners and 
operators of underground storage tanks (UST); approval of state underground storage tank programs. 

C. F. R. 40: Parts 280 and 281. 

Connor, B. F.; Rose, D. L.; Noriega, M. C.; Murtagh, L. K.; Abney, S. R. (1998) Methods of analysis by the 
U.S. Geological Survey National Water Quality Laboratory—determination of 86 volatile organic 
compounds in water by gas chromatography/mass spectrometry, including detections less than reporting 
limits. Denver, CO: U.S. Geological Survey; open-file report 97-829. 

Conrad, D. L.; Deever, W. R. (1995) The impacts of gasoline/oxygenate releases to the environment - a review of 
the literature. Port Arthur, TX: Texaco Research & Development Department. 

Corseuil, H. X.; Alvarez, P. J. J. (1996) Natural bioremediation perspective for BTX-contaminated groundwater in 
Brazil: effect of ethanol. Water Sci. Technol. 34: 311-318. 

Corseuil, H. X.; Aires, J. R.; Alvarez, P. J. J. (1996) Implications of the presence of ethanol on intrinsic 
bioremediation of BTX plumes in Brazil. Hazard. Waste Hazard. Mater. 13: 213-221. 

Corseuil, H. X.; Hunt, C. S.; Dos Santos, R. C. F.; Alvarez, P. J. J. (1998) The influence of the gasoline oxygenate 
ethanol on aerobic and anaerobic BTX biodegradation. Water Res. 32: 2065-2072. 

Curran, S. D. (1997) Permeability of synthetic membranes for the containment of petroleum products. Houston, 

TX: Fiberglass Tank & Pipe Institute; March. 

Dale, M. S.; Losee, R. F.; Crofts, E. W.; Davis, M. K. (1997) MTBE: occurrence and fate in source-water supplies. 
In: Preprints of papers presented at the 213th ACS national meeting; April; San Francisco, CA. Natl. Meet. 
Am. Chem. Soc. Div. Environ. Chem. 37: 376-377. 

Dalton, P. (1996) Odor perception and beliefs about risk. Chem. Senses 21: 447-458. 

Daughtrey, W. C.; Bird, M. G. (1995) Genotoxicity and twenty-eight-day subchronic toxicity studies on tertiary 
amyl methyl ether. J. Appl. Toxicol. 15: 313-319. 

Davidson, J. M. (1998) MTBE & underground storage tank systems: a question of compatibility. Wilmington, MA: 
New England Interstate Water Pollution Control Commission; pp. 18-21,30; LUSTline bulletin no. 28. 

Delzer, G. C.; Zogorski, J. S.; Lopes, T. J.; Bosshart, R. L. (1996) Occurrence of the gasoline oxygenate MTBE 
and BTEX compounds in urban stormwater in the United States, 1991-95. Rapid City, SD: U.S. Geological 
Survey; water-resources investigations report 96-4145. 

DeWitt & Company, Incorporated. (1997) MTBE and oxygenates: 1997 annual. Houston, TX: DeWitt & 

Company, Incorporated. 

Dorman, D. C.; Struve, M. F.; Wong, B. A.; Morgan, K. T.; Janszen, D. B.; Gross, E. B.; Bond, J. A. (1997) 

Neurotoxicological evaluation of ethyl tertiary-butyl ether following subchronic (90-day) inhalation in the 
Fischer 344 rat. J. Appl. Toxicol. 17: 235-242. 

Douthit, W. H.; Davis, B. C. (1988) 15% MTBE waiver request [submitted to Lee M. Thomas, U.S. Enviromental 
Protection Agency, Washington, DC], Sun Refining and Marketing Company. March. 


41 


Douthit, W. H.; Davis, B. C.; De Lieu Steinke, E.; Doherty, H. M. (1988) Performance features of 15% 

MTBE/gasoline blends. Warrendale, PA: Society of Automotive Engineers, Inc.; report no. 881667. 

Drake, D. E.; Gregory, L. R. Hotaling, A. C. (1995) Effect of MTBE and other oxygenates on FRP underground 
storage tanks - an interim report. 

Eichelberger, J. W.; Munch, J. W.; Bellar, T. A. (1992) Method 524.2. Measurement of purgeable organic 

compounds in water by capillary column gas chromatography/mass spectrometry: revision 4.0. Cincinnati, 
OH: U.S. Environmental Protection Agency, Office of Research and Development; August. 

European Centre for Ecotoxicology and Toxicology of Chemicals. (1997) Methyl tert-butyl ether (MTBE) health 
risk characterisation. Brussels, Belgium: ECETOC; technical report no. 72. 

Federal Register. (1995) Testing consent order for tertiary amyl methyl ether. F. R. (March 21) 54: 14910-14912. 

Federal Register. (1998) Announcement of the drinking water contaminant candidate list. F. R. (March 2) 

63: 10,273-10,287. 

Froines, J. R.; Collins, M.; Fanning, E.; McConnell, R.; Robbins, W.; Silver, K.; Kun, H.; Mutialu, R.; Okoji, R.; 
Taber, R.; Tareen, N.; Zandonella, C. (1998) An Evaluation of the scientific peer-reviewed research and 
literature on the human health effects of MTBE, its metabolites, combustion products and substitute 
compounds. In: Health and environmental assessment of MTBE: report to the Governor and legislature of 
the state of California as sponsored by SB 521. Volume II: human health effects. Davis, CA: University of 
California Toxic Substances Research & Teaching Program. Available online at: 
http://www.tsrtp.ucdavis.edu/mtbertp/homepage.html. 

Galperin, Y. (1998) Gasoline oxygenate analysis in environmental samples by two-dimensional gas 

chromatography. Presented at: West coast conference on contaminated soil and groundwater; March. 

Garrett, P. (1987) Oxygenates as ground water contaminants. Presented at: 1987 conference on alcohols and 
octane; April; San Antonio, TX. 

Georgopoulos, P. G.; Walia, A.; Roy, A.; Lioy, P. J. (1997) Integrated exposure and dose modeling and analysis 
system. 1. Formulation and testing of microenvironmental and pharmacokinetic components. Environ. Sci. 
Technol. 31: 17-27. 

Geraghty & Miller, Incorporated. (1996) MTBE contamination forces well closures. Groundwater Newsl. 

25(16): 1. 

Geyer, W. B. (1995) Compatibility of steel with oxygenated fuels. Presented at: American Petroleum Institute 

materials compatibility roundtable: an industry discussion; September; Cincinnati, OH. American Petroleum 
Institute. 

Giardino, N. J.; Andelman, J. B. (1996) Characterization of the emissions of trichloroethylene, chloroform, and 
l,2-dibromo-3-chloropropane in a full-size, experimental shower. J. Exposure Anal. Environ. Epidemiol. 

6: 413-423. 

Grady, S. J. (1997) Distribution of MTBE in ground water in New England by aquifer type and land use. In: 
Preprints of papers presented at the 213th ACS national meeting; April; San Francisco, CA. Natl. Meet. 

Am. Chem. Soc. Div. Environ. Chem. 37: 392-394. 

Grady, D.; Johnson, R. L. (1995) Vapor extraction of a contaminated fractured clay. In: Petroleum hydrocarbons 
and organic chemicals in ground water: prevention, detection and remediation, proceedings of a conference. 
Dublin, OH: National Ground Water Association; pp. 593-604. 


42 


Happel, A. M.; Beckenbach, E. H.; Halden, R. U. (1998) An evaluation of MTBE Impacts to California 

groundwater resources. Livermore, CA: Lawrence Livermore National Laboratory; UCRL-AR-130897. 

Health Effects Institute. (1996) The potential health effects of oxygenates added to gasoline: a review of the current 
literature, a special report of the Institute's Oxygenates Evaluation Committee. Cambridge, MA: Health 
Effects Institute, Oxygenates Evaluation Committee. 

Hitzig, R.; Kostecki, P.; Leonard, D. (1998) Study reports LUST programs are feeling effects of MTBE releases. 
Soil Groundwater Cleanup (Aug/Sept): 15-19. 

Hoff, J. T.; Gregor, D.; MacKay, D.; Wania, F.; Jia, C. Q. (1998) Measurement of the specific surface area of snow 
with the nitrogen adsorption technique. Environ. Sci. Technol. 32: 58-62. 

Hong, J.-Y.; Wang, Y.-Y.; Bondoc, F. Y.; Yang, C. S.; Lee, M.; Huang, W.-Q. (1997) Rat olfactory mucosa 

displays a high activity in metabolizing methyl tert -butyl ether and other gasoline ethers. Fundam. Appl. 
Toxicol. 40: 205-210. 

Hotaling, A. C. (1995) Evaluating nonmetallic materials' compatibility with MTBE and MTBE + gasoline service. 
In: American energy week '95 - pipelines, terminals & storage II: reformulated fuels conference 
proceedings. AST: special problems I; pp. 118-126. 

Hunt, C. S.; Alvarez, P. J. J.; Dos Santos Ferreira, R.; Corseuil, H. X. (1997) Effect of ethanol on aerobic BTX 
degradation. In: In situ and on-site bioremediation: volume 1. Papers from the fourth international in situ 
and on-site bioremediation symposium; April-May; New Orleans, LA. Columbus, OH: Battelle Press, pp. 
49-54. 

Huttunen, H.; Wyness, L. E.; Kalliokoski, P. (1997) Identification of environmental hazards of gasoline oxygenate 
ferf-amyl methyl ether (TAME). Chemosphere 35: 1199-1214. 

IIT Research Institute. (1992) Twenty-eight day oral (gavage) toxicity study of methyl ferf-butyl ether (MTBE) in 
rats [final report], Chicago, IL: IIT Research Institute; project no. L08100SN1602. 

Interagency Oxygenated Fuels Assessment Steering Committee. (1996) Interagency assessment of potential health 
risks associated with oxygenated gasoline. Washington, DC: National Science and Technology Council and 
Office of Science and Technology Policy. 

Interagency Oxygenated Fuels Assessment Steering Committee. (1997) Interagency assessment of oxygenated 

fuels. Washington, DC: National Science and Technology Council, Committee on Environment and Natural 
Resources and Office of Science and Technology Policy. 

International Agency for Research on Cancer. (1998) Evaluation or re-evaluation of some agents which target 
specific organs in rodent bioassays. In: Some agents affecting specific target organs in rodent bioassays. 
Lyon, France: International Agency for Research on Cancer; pp. 445-474. (IARC monographs on the 
evaluation of the carcinogenic risk of chemicals to humans: v. 73). Available online at: 
http://l 93.51.164.11 /default.html. 

Johanson, G.; Lof, A.; Nihlen, A.; Pekari, K.; Riihimki, V. (1997) Toxicokinetics of ethers in humans - a 
comparison of MTBE, ETBE, and TAME. In: Abstracts of the 36th annual meeting of the Society of 
Toxicology; March; Cincinnati, OH. Toxicologist 36(1, part 2): 339. 

Kang, J.-W.; Hoffmann, M. R. (1998) Kinetics and mechanism of the sonolytic destruction of methyl terf-butyl 
ether by ultrasonic irradiation in the presence of ozone. Environ. Sci. Technol. 32: 3194-3199. 


43 


Landmeyer, J. E.; Chapelle, F. H.; Bradley, P. M.; Pankow, J. F.; Church, C. D.; Tratnyek, P. G. (1998) Fate of 
MTBE relative to benzene in a gasoline-contaminated aquifer (1993-98). Ground Water Monit. Rem. 
[accepted]. 

Leitner, N. K. V.; Papailhou, A.-L.; Crou6, J.-P.; Peyrot, J.; Dore, M. (1994) Oxidation of methyl tert-butyl ether 
(MTBE) and ethyl tert-butyl ether (ETBE) by ozone and combined ozone/hydrogen peroxide. Ozone Sci. 
Eng. 16: 41-54. 

Lindsey, B. D.; Breen, K. J.; Daly, M. H. (1997) MTBE in water from fractured-bedrock aquifers, southcentral 
Pennsylvania. In: Preprints of papers presented at the 213th ACS national meeting; April; San Francisco, 
CA. Natl. Meet. Am. Chem. Soc. Div. Environ. Chem. 37: 399-400. 

Lindstrom, A. B.; Highsmith, V. R.; Buckley, T. J.; Pate, W. J.; Michael, L. C. (1994) Gasoline-contaminated 
ground water as a source of residential benzene exposure: a case study. J. Exposure Anal. Environ. 
Epidemiol. 4: 183-195. 

Maine Department of Human Services, Bureau of Health. (1998) Presence of MTBE and other gasoline compounds 
in Maine's drinking water: a preliminary report. Augusta, ME: Maine Department of Human Services, 
Bureau of Health; October 13. Available online at: www.state.me.us/dhs/boh/index2.htm. 

Malcolm Pimie Incorporated. (1997) Estimates of annual costs to remove MTBE from water for potable uses. 
Arlington, VA: Oxygenated Fuels Association, Inc.; technical memorandum. 

Malcolm Pimie, Incorporated. (1998a) Modeling the volatilization of methyl tertiary-butyl ether (MTBE) from 
surface impoundments. Arlington, VA: Oxygenated Fuels Association, Inc.; technical memorandum. 

Malcolm Pimie, Incorporated. (1998b) Taste and odor properties of methyl tertiary-butyl ether and implications for 
setting a secondary maximum contaminant level. Arlington, VA: Oxygenated Fuels Association, Inc.; report 
no. 3195-001-007. 

Malley, J. P.; Locandro, R. R.; Wagler, J. L. (1993) Innovative point-of-entry (POE) treatment for petroleum 
contaminated water supply wells. Final report. Durham, NH: U.S. Geological Survey, New Hampshire 
Water Resources Research Center. 

Mancini, E. R.; Arnold, W. R.; BenKinney, M. T.; Gostomski, F. E.; Rausina, G. A.; Steen, A.; Wong, D. C. L. 
(1998) MTBE water quality criteria database development: a collaborative effort. Presented at: The natural 
connection: environmental integrity and human health. SETAC 19th annual meeting, poster session; 
November; Charlotte, NC. Pensacola, FL: Society of Environmental Toxicology and Chemistry; PHA149. 

McKinnon, R. J.; Dyksen, J. E. (1984) Removing organics from groundwater through aeration plus GAC. J. Am. 
Water Works Assoc. 76: 42- 47. 

McKone, T. E.; Knezovich, J. P. (1991) The transfer of trichloroethylene (TCE) from a shower to indoor air: 
experimental measurements and their implications. J. Air Waste Manage. Assoc. 41: 832-837. 

Meli, P. I., Jr. (1996) [Letter to Ms. Sonya Harrigfeld concerning Bridgeport Chemical Group's GA 27P 
underground storage tank lining product], Pompano Beach, FL: Industrial Environmental Coatings 
Corporation; August, 14. 

Mormile, M. R.; Liu, S.; Suflita, J. M. (1994) Anaerobic biodegradation of gasoline oxygenates: extrapolation of 
information to multiple sites and redox conditions. Environ. Sci. Technol. 28: 1727-1732. 


44 


National Research Council; Committee on Toxicological and Performance Aspects of Oxygenated and 

Reformulated Motor Vehicle Fuels. (1996) Toxicological and performance aspects of oxygenated motor 
vehicle fuels. Washington, DC: National Academy Press. 

Pankow, J. F.; Thomson, N. R.; Johnson, R. L.; Baehr, A. L.; Zogorski, J. S. (1997) The urban atmosphere as a 
non-point source for the transport of MTBE and other volatile organic compounds (VOCs) to shallow 
groundwater. In: Preprints of papers presented at the 213th ACS national meeting; April; San Francisco, 
CA. Natl. Meet. Am. Chem. Soc. Div. Environ. Chem. 37: 385-387. 

Petroleum Environmental Research Forum. (1993) Aerobic biodegradation of MTBE - basic fate of biokinetics 
evaluation, final report of PERF project 90-10, June, 1993. 

Piver, W. T.; Jacobs, T. L.; Medina, M. A., Jr. (1997) Evaluation of health risks for contaminated aquifers. 
Environ. Flealth Perspect. 105(suppl. 1): 127-143. 

Prah, J. D.; Goldstein, G. M.; Devlin, R.; Otto, D.; Ashley, D.; House, D.; Cohen, K. L.; Gerrity, T. (1994) 

Sensory, symptomatic, inflammatory, and ocular responses to and the metabolism of methyl tertiary butyl 
ether in a controlled human exposure experiment. Inhalation Toxicol. 6: 521-538. 

Rao, H. V.; Ginsberg, G. L. (1997) A physiologically-based pharmacokinetic model assessment of methyl f-butyl 
ether in groundwater for a bathing and showering determination. Risk Anal. 17: 583-598. 

Reuter, J. E.; Allen, B. C.; Richards, R. C.; Pankow, J. F.; Goldman, C. R.; Scholl, R. L.; Seyffied, J. S. (1998) 
Concentrations, sources, and fate of the gasoline oxygenate methyl terf-butyl ether (MTBE) in a 
multiple-use lake. Environ. Sci. Technol. 32: 3666-3672. 

Rhodes, I.; Milazzo, J.; Brzuzy, L.; Harvey, L.; Verstuyft, A.; Halden, R.; Schoen, S.; Galperin, Y.; Kaplan, I.; 
Happel, A. (1998) Analytical methods for the determination of oxygenates in gasoline-contaminated 
groundwater: modified EPA and ASTM methods. Presented at: 21st annual EPA conference on analysis of 
pollutants in the environment; May; Norfolk, VA. 

Robinson, M.; Bruner, R. H.; Olson, G. R. (1990) Fourteen- and ninety-day oral toxicity studies of methyl 
tertiary-butyl ether in Sprague-Dawley rats. J. Am. Coll. Toxicol. 9: 525-540. 

Salanitro, J. P.; Diaz, L. A.; Williams, M. P.; Wisniewski, H. L. (1994) Isolation of a bacterial culture that 
degrades methyl t-butyl ether. Appl. Environ. Microbiol. 60: 2593-2596. 

Schirmer, M.; Barker, J. F. (1998) A study of long-term MTBE attenuation in the Borden Aquifer, Ontario, 
Canada. Ground Water Monit. Rem. 18: 113-122. 

Shen, Y. F.; Yoo, L. J.; Fitzsimmons, S. R.; Yamamoto, M. K. (1997) Threshold odor concentrations of MTBE 
and other fuel oxygenates. In: Preprints of papers presented at the 213th American Chemical Society 
national meeting; April; San Francisco, CA; pp. 407-409. (ACS Division of Environmental Chemistry: 
v. 37) 

Siddiqui, M.; LeChevallier, M. W.; Ban, J.; Phillips, T.; Pivinski, J. (1998) Occurrence of perchlorate and methyl 
tertiary butyl ether (MTBE) in groundwater of the American water system. Vorhees, NJ: American Water 
Works Service Company, Inc.; September 30. 

Smith Fiberglass Products, Inc. (1996) Just the facts [permeability testing of piping systems manufactured by 
Smith Fiberglass Products]. Little Rock, AR: Smith Fiberglass Products, Inc. 

Smith, D. F.; Kleindienst, T. E.; Hudgens, E. E.; Mclver, C. D.; Bufalini, J. J. (1991) The photooxidation of 
methyl tertiary butyl ether. Int. J. Chem. Kinet. 23: 907-924. 


45 


Speth, T. F.; Miltner, R. J. (1990) Technical note: adsorption capacity of GAC for synthetic organics. J. Am. Water 
Works Assoc. 82: 72-75. 

Squillace, P. J.; Zogorski, J. S.; Wilber, W. G.; Price, C. V. (1996) Preliminary assessment of the occurrence and 
possible sources of MTBE in groundwater in the United States, 1993-1994. Environ. Sci. Technol. 

30: 1721-1730. 

Squillace, P. J.; Zogorski, J. S.; Price, C. V.; Wilber, W. G. (1997) Preliminary assessment of the occurrence and 
possible sources of MTBE in groundwater in the United States, 1993-94. In: Chilton, J.; et al, eds. 
Groundwater in the urban environment. Volume 1: problems, processes and management. Rotterdam, 

The Netherlands: A. A. Balkema; pp. 537-542. 

Stackelberg, P. E.; O'Brien, A. K.; Terracciano, S. A. (1997) Occurrence of MTBE in surface and ground water, 
Long Island, New York, and New Jersey. In: Preprints of papers presented at the 213th ACS national 
meeting; April; San Francisco, CA. Natl. Meet. Am. Chem. Soc. Div. Environ. Chem. 37: 394-397. 

Steffan, R. J.; McClay, K.; Vainberg, S.; Condee, C. W.; Zhang, D. (1997) Biodegradation of the gasoline 

oxygenates methyl tert -butyl ether, ethyl ferf-butyl ether, and fert-amyl methyl ether by propane-oxidizing 
bacteria. Appl. Environ. Microbiol. 63: 4216-4222. 

Suflita, J. M.; Mormile, M. R. (1993) Anaerobic biodegradation of known and potential gasoline oxygenates in the 
terrestrial subsurface. Environ. Sci. Technol. 27: 976-978. 

TRC Environmental Corporation. (1993) Odor threshold studies performed with gasoline and gasoline combined 
with MTBE, ETBE and TAME. Washington, DC: American Petroleum Institute; API publication no. 4592. 

Tennant, R. W.; French, J. E.; Spalding, J. W. (1995) Identitying chemical carcinogens and assessing potential 
risk in short-term bioassays using transgenic mouse models. Environ. Health Perspect. 103: 942-950. 

Truong, K. N.; Parmele, C. S. (1992) Cost-effective alternative treatment technologies for reducing the 

concentrations of methyl tertiary butyl ether and methanol in groundwater. In: Calabrese, E. J.; Kostecki, 

P. T., eds. Hydrocarbon contaminated soils and groundwater: v. 2. Boca Raton, Fi: Lewis Publishers; 
pp. 461-486. 

U. S. Code. (1977) Clean Water Act. U. S. C. 33: §305(b). 

U.S. Code. (1990) Clean Air Act, §211, regulation of fuels: (k) reformulated gasoline for conventional vehicles; 

(m) oxygenated fuels. U. S. C. 42: §7545. 

U.S. Code. (1996) Safe Drinking Water Act, as amended by PL 104-208, September 30. U. S. C. 42: §300f et seq. 

U.S. Department of Energy. (1995) Petroleum supply annual 1995: volume 1. Washington, DC: Energy 
Information Administration, Office of Oil & Gas; report no. DOE/EIA-0340(95). 

U.S. Environmental Protection Agency. (1992) Alternative fuels research strategy [external review draft], 
Washington, DC: Office of Research and Development; report no. EPA/600/AP-92/002. 

U.S. Environmental Protection Agency. (1993) Assessment of potential risks of gasoline oxygenated with methyl 
tertiary butyl ether (MTBE). Washington, DC: Office of Research and Development; November; report no. 
EPA/600/R-93/206. 

U.S. Environmental Protection Agency. (1994) Health risk perspectives on fuel oxygenates. Washington, DC: 

Office of Research and Development; report no. EPA 600/R-94/217. 


46 


U.S. Environmental Protection Agency. (1996) Oxyfuels information needs. Research Triangle Park, NC: National 
Center for Environmental Assessment; report no. EPA/600/R-96/069. Available from: NTIS, Springfield, 
VA; PB96-190665REB. 

U.S. Environmental Protection Agency. (1997) Drinking water advisory: consumer acceptability advice and health 
effects analysis on methyl tertiary-butyl ether (MTBE). Washington, DC: Office of Water; report no. 
EPA-822-F-97-008. 

U.S. Environmental Protection Agency. (1998a) 1996 toxics release inventory public data release. Washington, 

DC: Office of Pollution Prevention and Toxics; pp. 19-284. Available online at: 
http://www.epa.gov/opptintr/tri/index.html. 

U.S. Environmental Protection Agency. (1998b) Appendix A to part 136: methods for organic chemical analysis of 
municipal and industrial wastewater. Method 624—purgeables. Washington, DC: Office of Water; August 
24. Available online at: www.epa.gov/OST/Tools/guide/methods.html. 

U.S. Environmental Protection Agency. (1998c) Method 8260B: volatile organic compounds by gas 

chromatography/mass spectrometry (GC/MS). Washington, DC: Office of Solid Waste. Available online at: 
www.epa.gov/epaoswer/hazwaste/test/8xxx.htm. 

U.S. Environmental Protection Agency. (1998d) Final notification letter to API of testing requirements for baseline 
gasoline and non-baseline (oxygenated) gasoline groups under section 211(b) of the Clean Air Act [letter 
from Margo T. Oge, Director, Office of Mobile Sources to Carol Henry, Director, Health and Environmental 
Science Department, American Petroleum Institute]. Washington, DC: Office of Mobile Sources; November 
2. Available online at: http://www.epa.gov/oms/consumer/fuels/mtbe/mtbe.htm. 

Vetrano, K. (1993a) Odor and taste threshold studies performed with tertiary-amyl methyl ether (TAME). 
Washington, DC: American Petroleum Institute; API publication 4591. 

Vetrano, K. M. (1993b) Final report to ARCO Chemical Company on the odor and taste threshold studies 

performed with methyl tertiary-butyl ether (MTBE) and ethyl tertiary-butyl ether (ETBE). Windsor, CT: 
TRC Environmental Corporation; project no. 13442-M31. 

Wallington, T. J.; Dagaut, P.; Liu, R.; Kurylo, M. J. (1988) Gas-phase reactions of hydroxyl radicals with the fuel 
additives methyl terf-butyl ether and ferf-butyl alcohol over the temperature range 240-440 K. Environ. Sci. 
Technol. 22: 842-844. 

Weisel, C. P.; Jo, W.-K. (1996) Ingestion, inhalation, and dermal exposures to chloroform and trichloroethene 
from tap water. Environ. Health Perspect. 104: 48-51. 

Wilkes, C. R.; Small, M. J.; Davidson, C. I.; Andelman, J. B. (1996) Modeling the effects of water usage and 

co-behavior on inhalation exposures to contaminants volatilized from household water. J. Exposure Anal. 
Environ. Epidemiol. 6: 393-412. 

Wybomy, L. A., II. (1997) Oxy-water res strategy question -reply [email memorandum to J. Michael Davis, U.S. 
EPA, RTP, NC]. Ann Arbor, MI: U.S. Environmental Protection Agency, Office of Mobile Sources; August 
18. 

Wyborny, L., II. (1998) Methyl tertiary butyl ether (MTBE) emissions from passenger cars [draft technical report]. 
Ann Arbor, MI: U.S. Environmental Protection Agency, Office of Mobile Sources. 

Yeh, K.-J. (1992) Degradation of gasoline oxygenates in the subsurface [dissertation]. Blacksburg, VA: Virginia 
Polytechnic Institute. 


47 


Young, W. F.; Horth, H.; Crane, R.; Ogden, T.; Amott, M. (1996) Taste and odour threshold concentrations of 
potential potable water contaminants. Water Res. 30: 331-340. 

Zogorski, J. S.; Delzer, G. C.; Bender, D. A.; Squillace, P. J.; Lopes, T. J.; Baehr, A. L.; Stackelberg, P. E.; 
Landmeyer, J. E.; Boughton, C. J.; Lico, M. S.; Pankow, J. F.; Johnson, R. L.; Thomson, N. R. (1998) 
MTBE: summary of findings and research by the U.S. Geological Survey. In: Proceedings of the 1998 
annual conference of the American Water Works Association [in press]. 


48 


APPENDIX 1 


CHEMICAL PROPERTIES OF SELECTED OXYGENATES 


Chemical Name 

Methyl Tertiary 
Butyl Ether 

Ethyl Tertiary 
Butyl Ether 

Tertiary Amyl 
Methyl Ether 

Diisopropyl 

Ether 

CAS Registry No. 

1634-04-4 

637-92-3 

994-05-8 

108-20-3 

Synonyms 

MTBE; 2-methyl, 
2-methoxy propane; 
tert-butyl methyl 
ether; methyl tert 
butyl ether; 
methyl-tert-butyl 
ether 

ETBE; tert-butyl 
ethyl ether; propane, 
2-ethoxy-2methyl; 

1, 1-dimethyl ethyl 
ether 

TAME; 2-methoxy-2 
methylbutane; methyl 
tert-pentyl ether; 
1,1-dimethylpropyl 
methyl ether; methyl 
tert-amyl ether 

DIPE; 2'2- 
oxybispropane; 
2-isopropoxy- 
propane 

Molecular 

Weight (g/mol) 

88.15 

102.18 

102.18 

102.18 

Molecular 

Formula 

c 5 h I2 o 

c 6 h 14 o 

c 6 h I4 o 

c 6 h 14 o 

Structural 

Formula 

CH 3 OC(CH 3 ) 3 

(CH 3 ) 3 COCH 2 CH 3 

CH 3 CH 2 C(CH 3 ) 2 OCH 3 

(CH 3 ) 2 CHOCH 

(CH 3 ) 2 

Boiling Point 
(at 760 mm Hg) 

55.2 °C 

72.2 °C 

86.3 °C 

68.2 °C 

Vapor Pressure 
(mm Hg at 

20 °C) 

240 

130 

75 

159 

Vapor Density 
(air = 1) 

3.1 

3.6 

3.6 

3.6 

Density 

(g/ml at 20 °C) 

0.74 

0.74 

0.77 

0.73 

Solubility 
(g/100 g water) 

4.8 

1.2 

1.2 

0.2 

Henry’s Law 
Constant 





(Atm-m 3 )/ 

(g-mole) 

5.28E-4 to 3E-3 

2.64E-3 

1.95E-3 

4.77E-3 

Dimensionless 

2.2E-2 to 1.2E-1 

0.11 

0.081 

0.199 

Log Koc 

0.55 to 0.91 

NA 

NA 

1.13 

Log Ko W 

0.94 to 1.30 

NA 

NA 

1.52 


49 

















CHEMICAL PROPERTIES OF SELECTED OXYGENATES (cont’d) 


Chemical Name 

Tertiary Amyl Ethyl 
Ether 

Dimethyl Ether 

Tertiary Butanol 

Ethanol 

CAS Registry No. 

919-94-8 

115-10-6 

75-65-0 

64-17-5 

Synonyms 

TAEE; ethyl tert-amyl 
ether; butane, 
2-ethoxy-2-methyl 

DME; methane, 
oxybis 

TBA; tertiary butyl 
alcohol; 2-propanol, 
2-methyl 

ethanol; 
ethyl alcohol 

Molecular 

Weight (g/mol) 

116.20 

46.07 

74.12 

46.07 

Molecular 

Formula 

c 7 h 16 o 

c 2 h,o 

c 4 h 10 o 

c 2 h 6 o 

Structural 

Formula 

CH 3 CH 2 C(CH 3 ) 2 OCH 2 C 

h 3 

ch 3 och 3 

(CH 3 ) 3 COH 

ch 3 ch 2 oh 

Boiling Point 
(at 760 mm Hg) 

102 °C 

-24.8 °C 

82.4 °C 

78.5 °C 

Vapor Pressure 
(mm Hg at 20 °C) 

NA 

758 to 5086’ 

41 

44 

Vapor Density 
(air- 1) 

4.0 

1.6 

2.6 

1.6 

Density 

(g/mL at 20 °C) 

0.75 

0.66 

0.79 

0.79 

Solubility 
(g/100 g water) 

NA 

4.7 to 35.3 

miscible 

miscible 


Henry’s Law 
Constant 


(Atm-m 3 )/ 

(g-mole) 

NA 

4.89E-4 to 9.97E-4 

1.21E-5 

6.91E-6 

Dimensionless 

NA 

2.03E-2 to 4.15E-2 

5.03E-4 

2.83E-4 


Log 

NA 

-0.29 

1.57 

-0.14 

Log K„ w 

NA 

0.10 

0.35 

-0.32 


’At 25°C 


50 

















APPENDIX 2 


CURRENT PROJECTS RELATED TO 
OXYGENATES IN WATER 

This list of projects and activities is organized alphabetically according to the organizations 
conducting and/or sponsoring the work. Contact persons are identified parenthetically for 
obtaining further details, followed by a short title, brief description, and status of the project. 
After each item, topic identifiers are included for cross referencing to areas of needed work 
identified in the base document. This list was completed in December 1998 with the intention of 
being as complete and accurate as possible. However, given the breadth and dynamic nature of 
this area of work, some omissions and errors may have occurred. 


Alpine Environmental (James Davidson) 

MTBE Remediation; An Evaluation of Technologies, Field Experience, and Case Studies. 

Review and analysis of remediation technologies applicable for MTBE; discusses both theory 
and actual case studies [American Petroleum Institute report, in press]. 

Contaminant Removal; Assessment 

American Petroleum Institute (H. Hopkins) 

MTBE Site Characterization Technical Bulletin. 

Describes approaches for characterizing and monitoring subsurface MTBE sources and plumes, 
highlighting differences between MTBE and BTEX [expected completion second quarter 1999], 
Source Characterization; Transport; Transformation 

Association of California Water Agencies; Western States Petroleum Association; 
Oxygenated Fuels Association; California Environmental Protection Agency; U.S. 
Environmental Protection Agency (Krista Clark, ACWA; Dave Smith, ARCO) 

MTBE Treatability Research Partnership. 

Joint research program to evaluate existing and emerging treatment technologies to remove 
MTBE from public drinking water supplies [report expected by mid-1999], 

Contaminant Removal 

Chemical Industry Institute of Toxicology; Oxygenated Fuels Association (Susan Borghoff, 
CUT; John Kneiss, OF A) 

MTBE Cancer Mechanisms. 

Study of role of alpha-2u-globulin in MTBE-induced kidney tumors in male rats [report expected 
late 1998], 

Health Effects 


51 


Environmental and Occupational Health Sciences Institute; ARCO Chemical; State of New 
Jersey (Paul Lioy, Nancy Fiedler, EOHSI) 

Inhalation Chamber Study of MTBE in Humans. 

Inhalation exposure to MTBE in gasoline evaluated in controls and in subjects self-described as 
sensitive to MTBE; although only inhalation route used, results might be relevant to other routes 
[expected completion early 1999]. 

Health Effects 

European Union; Finnish Environmental Institute; Finnish National Product Control 
Agency for Welfare and Health (Riitta Leinonen, FEI) 

MTBE Risk Assessment. 

Assessment of environmental and health risks of MTBE under Commission directive 93/67/EEC 
[publication expected 1999]. 

Assessment 

International Agency for Research on Cancer (Julian Wilboume) 

MTBE Monograph. 

Evaluation of carcinogenic risks of MTBE to humans [workgroup review October 1998; 
publication 1999]. 

Assessment 

Lawrence Livermore National Laboratory; American Petroleum Institute (Anne Happel, 
LLNL; Bruce Bauman, API) 

Study of MTBE and BTEX Plumes at Califomia/UST Release Sites. 

Characterize trends in the attenuation, magnitude of impact, and mobility of MTBE plumes in 
groundwater as compared to BTEX and evaluate the effectiveness of tank upgrades in preventing 
MTBE impacts [expected completion first quarter 2000]. 

Transport; Transformation; Release Prevention 

Lovelace Respiratory Research Institute; Health Effects Institute (Janet Benson, LRRI; 

Maria Costantini, HEI) 

Toxicokinetics of MTBE With and Without Gasoline. 

Quantify uptake, metabolism, and excretion of C-14 labeled MTBE alone and in gasoline over a 
range of concentrations and repeated inhalation exposures in rats [ongoing through 1998]. 
Health Effects 

Metcalf & Eddy; American Petroleum Institute (R. Claff, API) 

Characterization of Service Station Stormwater Runoff. 

Contractor to develop sampling plan to collect stormwater samples at several retail marketing 
facilities; samples to be analyzed for BTEX, MTBE, heavy metals, and a variety of other 
parameters [draft report expected late 1998]. 

Source Characterization; Occurrence 


52 


Metropolitan Water District of Southern California (Marshall Davis) 

Surface Water Sampling. 

Sampling for MTBE and other gasoline components in drinking water reservoirs used for 
recreational boating [ongoing through 1998]. 

Occurrence; Source Characterization 

Metropolitan Water District of Southern California; U.S. Geological Survey; American 
Water Works Association Research Foundation (Bart Koch, MWDSC; Kenan Ozekin, 
AWWARF) 

Sampling of Public Drinking Water Supplies. 

Nation-wide sampling of source waters for community water systems to characterize MTBE 
contamination [expected completion 1999]. 

Occurrence; Exposure 

MTBE Water Quality Criteria Workgroup (American Petroleum Institute) (Gene Mancini, 
ARCO; Alexis Steen, API) 

Eco/aquatic Biota Toxicity. 

After literature search to determine gaps in aquatic toxicity database, testing to develop data set 
to enable EPA to determine acute and chronic water quality criteria for MTBE in both fresh 
water and marine environments [report expected early 1999]. 

Aquatic Toxicity 

National Research Council, Water Science and Technology Board (J. McDonald) 

Intrinsic Remediation Study. 

Assessment of current scientific understanding of natural processes that degrade or immobilize 
contaminants, including oxygenates, in soil and groundwater [report expected November 1999]. 
Assessment 

National Toxicology Program (C.W. Jameson, NTP-NIEHS) 

Proposed Listing of MTBE. 

NTP to review recommendations of review committees and public comments regarding 
recommendations to the Secretary, DHHS, for listing MTBE in the Ninth Edition of the “Report 
on Carcinogens; ” in December 1998 review, NTP Board of Scientific Counselors Subcommittee 
voted against motion to list MTBE as “reasonably anticipated to be a human carcinogen; ” final 
public comment period open until February 15, 1999 [current status available at: 
http://ntp-server.niehs.nih.gov/]. 

Assessment 

North Carolina State University; American Petroleum Institute (M. Hyman, NCSU; Bruce 
Bauman, API) 

Cometabolism of Gasoline Oxygenates by Alkane-Utilizing Bacteria. 

Evaluate and quantify the role of gasoline alkanes as stimulators, inhibitors, and regulators of 
in situ bacterial cometabolic biodegradation of MTBE in soil and groundwater [completion 
third quarter 2000]. 

Transformation 


53 


North Carolina State University; American Petroleum Institute (Robert Borden, NCSU; 
Bruce Bauman, API) 

Monitoring Degradation: Sampson County, NC. 

Monitoring degradation ofMTBE, BTEX in plume from UST in shallow coastal aquifer in 
Sampson County, NC; leak discovered -1986, remediated 1990 [ see: Borden, et al., Intrinsic 
biodegradation ofMTBE and BTEX in a gasoline-contaminated aquifer. Water Resour. Res. 33: 
1105-1115, 1997; Borden et al., Field studies of BTEX and MTBE intrinsic bioremediation. 
Washington, DC: American Petroleum Institute; Health and Environmental Sciences 
Department. API publication no. 4654, 1997; final report expected late 1998]. 

Transport; Transformation 

Oregon Graduate Institute; American Petroleum Institute (Rick Johnson, OGI; 

Bruce Bauman, API) 

Removal ofMTBE from a Residual Gasoline Source through in situ Air Sparging. 

Evaluate the effectiveness of in situ air sparging to remove MTBE from source zone and the 
extent that such treatment results in reduction in MTBE in groundwater downgradient [expected 
completion early 1999]. 

Contaminant Removal; Transport; Transformation 

Oregon Graduate Institute; Arizona State University; American Petroleum Institute 

(H. Hopkins, OGI; Bruce Bauman, API) 

Field Tracer Experiment at Port Hueneme, CA. 

Deuterated MTBE and tracer injected into existing MTBE plume followed by quarterly sampling 
for 1-2 years to determine changes attributable to biodegradation [report expected early 1999]. 
Transport; Transformation 

Rutgers University; American Petroleum Institute (R. Cowan, RU; Bruce Bauman, API) 

Ex Situ Biological Treatment of Water Containing MTBE. 

Development of technology to biologically treat MTBE-contaminated water ex situ [ongoing 
through 2000; interim report expected late 1998]. 

Contaminant Removal 

Rutgers University; Health Effects Institute (Jun-Yan Hong, RU; Maria Costantini, HEI) 

Role of Human Cytochrome P450 2E1 in Metabolism and Health Effects of Gasoline Ethers. 
Characterize metabolism ofMTBE and other ethers in human liver microsomes, with attention to 
role of CYP 2E1 and its genotypic distribution in humans; compare ether metabolism in human 
liver microsomes versus rat and monkey nasal mucosa microsomes, to illuminate relevance of 
animal studies to humans [ongoing through 1998]. 

Health Effects 

Shell Development Corporation (J.P. Salanitro) 

MTBE Bioremediation. 

Isolation of bacterial culture capable of degrading MTBE in groundwater [ongoing]. 
Contaminant Removal; Transport; Transformation 


54 


Shell Development Corporation (P.A. Westbrook) 

Polymer-Solvent Interactions. 

Prediction of polymer/elastomer response to MTBE-gasoline blends based on response to neat 
MTBE [see: Westbrook, P. A. and French, R. N., Elastomer swelling in mixed solvents, Rubber 
Chem. Technol. (in press); other reports in preparation]. 

Release Prevention 

State of California, Department of Health Services (Steven Book) 

Drinking Water Standards for MTBE. 

Secondary and primary maximum contaminant levels (MCLs) for MTBE in drinking water to be 
established as required by 1997 state law; proposed secondary MCL of 5 pg/L to protect public 
from exposure to MTBE in drinking water at levels than can be smelled or tasted; proposed 
primary MCL, in preparation, to utilize Public Health Goal developed by California EPA's 
Office of Environmental Health Hazard Assessment (see separate listing) [secondary MCL 
adopted November 12, 1998 and currently under review by California OfTice of Administrative 
Law; proposed primary MCL to be released for public comment in spring 1999]. 

Assessment; Risk Management 

State of California, Department of Health Services; U.S. Environmental Protection Agency- 
Region 9 (Leah Walker, CA DHS; Judy Bloom, EPA-Region 9) 

California Drinking Water Source Assessment Program. 

Compile data for MTBE in ground/surface source water from State Drinking Water programs; 
evaluate vulnerability to contamination and need for further assessment [ongoing; data 
available at http://www.dhs.cahwnet.gov/org/ps/ddwem]. 

Occurrence 

State of California, Environmental Protection Agency, Office of Environmental Health 
Hazard Assessment (Juliet Rafol) 

Public Health Goal for MTBE. 

PHG for MTBE in drinking water intended to pose no significant risk to individuals, including 
most sensitive subpopulations, consuming the water daily over a lifetime; PHG considered by 
California Department of Health Services in setting primary MCL for drinking water; draft 
value, 14 pg/L [report to California Legislature due January 1999]. 

Assessment 

State of California, Environmental Protection Agency, Office of Environmental Health 
Hazard Assessment (Susan Luong) 

Proposition 65 Listing. 

Science Advisory Board subcommittees evaluate whether MTBE meets criteria under California 
Proposition 65 for listing as "known to the state to cause cancer or reproductive toxicity" 
[subcommittees voted December 1998 not to list MTBE as either a carcinogen or reproductive 
toxicant]. 

Assessment 


55 


State of California Regional Water Quality Control Board; Lawrence Livermore National 
Laboratory; U.S. Environmental Protection Agency-Region 9 (Heidi Temko, CA RWQCB; 
Anne Happel, LLNL; Matt Small, EPA) 

California GIS Mapping and Data Management Advisory Committee 

Provide Governor's Office, legislature, and public entities with information on vulnerability of 
Calif groundwater to MTBE; initiate state-wide geographical information system (GIS) to 
manage risk of MTBE contamination to groundwater supplies; investigate in two pilot project 
areas the feasibility and appropriateness of establishing a state-wide GIS mapping system 
[estimated completion June 1999; data available at http://www-erd.llnl.gov/mtbe/]. 

Source Characterization; Occurrence 

State of California; University of California (Arturo Keller, UC-Santa Barbara) 

Health and Environmental Assessment of MTBE. 

As mandated by California State Legislature appropriating funds to the University of California, 
specific areas of study and reports as follow: (1) Evaluation of the Peer-reviewed Research 
Literature on the Human Health, including Asthma, and Environmental Effects of MTBE, John 
Froines, UCLA; (2) Integrated Assessment of Sources, Fate & Transport, Ecological Risk and 
Control Options for MTBE in Surface and Ground Waters, with Particular Emphasis on 
Drinking Water Supplies, John Reuter and Daniel Chang, UC-D; (3) Evaluation of Costs and 
Effectiveness of Treatment Technologies Applicable to Remove MTBE and Other Gasoline 
Oxygenates from Contaminated Water, Arturo Keller, UCSB; (4) Drinking Water Treatment for 
the Removal of Methyl Tertiary Butyl Ether from Ground Waters and Surface Water Reservoirs, 
Irwin Suffet, UCLA; (5) Evaluation of MTBE Combustion Byproducts in California 
Reformulated Gasoline, Catherine Koshland, UCSB; and (6) Risk-based Decision Making 
Analysis of the Cost and Benefits of MTBE and Other Gasoline Oxygenates, Arturo Keller, 

UCSB [initial report released November, 1998; final report expected spring 1999; report 
available at: http://tsrtp.ucdavis.edu/mtberpt]. 

Assessment 

State of Maine; Departments of Human Services, Environmental Protection, Conservation 

(Andrew Smith, Bureau of Health, Maine DHS) 

Monitoring Public and Private Water Supplies: Maine. 

Preliminary results of random statewide monitoring for MTBE and other gasoline constituents in 
public and private drinking water supplies statewide [preliminary report available at 
http://www.state.me.us/dep/blwq/gw.htm; final report expected early 1999]. 

Occurrence 

University of California-Davis (John E. Reuter) 

Sources, Fate, and Transport of MTBE in Sierra Nevada Multiple Use Lakes. 

Study of sources, transport, and fate of MTBE in Lake Tahoe and Donner Lake [ongoing; see 
Reuter et al., Concentrations, sources, and fate of the gasoline oxygenate methyl tert-butyl ether 
(MTBE) in a multiple-use lake, Environ. Sci. Techno! 32: 3666-3672, 1998]. 

Transport; Transformation; Source Characterization 


56 


University of California-Davis; American Petroleum Institute (E. Schroeder, UC; 

Bruce Bauman, API) 

Vapor Phase Biodegradation of MTBE. 

Evaluate effectiveness of biofilters in MTBE vapor phase treatment; culture aerobic, natural 
microbial consortium that rapidly degrades MTBE, uses MTBE as its sole carbon and energy 
source, and has been shown (Eweis et al., Proceedings 9(J h AWMA Meeting, Toronto, June 8-13, 
1997) to degrade MTBE in both liquid and gas streams (biofilters); assess impact of other 
organics (e.g., aromatics, alkanes) on MTBE biodegradation; characterize potential limitations 
of technology [report expected second quarter 1999], 

Contaminant Removal 

University of California-Davis; EPA-OSWER-OUST (Thomas Young, UC; David Wiley, 
EPA-OSWER-OUST) 

Field Verification of UST System Leak Detection Performance. 

Evaluate data from UST closures and release investigations from approximately 16 state 
environmental agencies to (1) quantify probability of types of leak detection failures (missed 
detections, false alarms) for different methods and equipment brands, and (2) understand 
sources of failure (e.g., human error, mechanical failure, environmental variables) [report and 
database expected late 1999]. 

Release Prevention 

University of Houston; American Petroleum Institute (William G. Rixey, UH; Bruce Bauman, 
API) 

Characteristics of MTBE from a Gasoline Source. 

Characterize dissolution and desorption of MTBE from a gasoline source residually trapped in 
soil; assess duration of MTBE in source area; leaching behavior evaluated in laboratory 
fixed-bed columns and results modeled [expected completion late 1998]. 

Transport; Transformation 

University of Massachusetts-Amherst; American Petroleum Institute (Derek Lovley, UM; 
Bruce Bauman, API) 

Anaerobic Degradation of MTBE, BTEX, and PAHs in Petroleum-Contaminated Aquifers. 
Determine: 1) potential for ferric iron to serve as electron acceptor for anaerobic 
biodegradation of MTBE and BTEX in groundwater and rates associated with this process in 
variety of aquifers; 2) anaerobic processes in the source area of fuel spills; 3) anaerobic 
biodegradability of PAHs in groundwater [report expected late 1999]. 

Transport; Transformation; Contaminant Removal 

University of Medicine and Dentistry of New Jersey (Clifford P. Weisel) 

Modulation of Benzene Metabolism by Exposure to Environmental Mixtures 
Evaluate (1) metabolism of benzene when inhaled by humans alone or as part of a mixture of 
MTBE or metals such as iron, and (2) in vitro toxicity of metabolites of mixtures such as benzene 
and MTBE [ongoing]. 

Health Effects 


57 


University of Michigan-National Center for Integrated Bioremediation (Michael Barcelona) 
MTBE Behavior in BTEX Plume. 

Characterize natural fate and transport of dissolved MTBE/BTEX under different shallow 
groundwater redox regimes, and effects of oxygen-releasing material; information on the 
evolution of microbial ecology also to be collected [expected completion fourth quarter 1999]. 
Transport; Transformation 

University of Nebraska (H. Noureddini) 

Remediation Efficiency for ETBE compared to MTBE. 

Comparative experimental studies of removal of ETBE and MTBE from contaminated water by 
air stripping and carbon adsorption; literature review of available ETBE research data 
[ongoing; unpublished report available upon request]. 

Contaminant Removal 

University of Nevada-Reno (Glenn Miller) 

Sampling for MTBE in Lake Tahoe. 

Sample for MTBE from various depths and locations, including temperature and meteorology 
data; evaluate MTBE and BTEX contamination from watercraft [ongoing]. 

Occurrence; Source Characterization; Transport; Transformation 

University of Northern Iowa; Exxon (C. M. Horan, UNI) 

Effect of MTBE on Microbial Consortia. 

MTBE added to microbial consortia increased oxygen consumption, but concentrations up to 
740 mg/L inhibited mineralization potential of hexadecane up to 50%; although MTBE can be 
metabolized in environment, toxicity may adversely affect overall biodegradation of fuel HCs 
[ongoing; report available at http://www.engg.ksu.edu/HSRC/95Proceed/horan.html]. 
Contaminant Removal; Transport; Transformation 

University of Notre Dame; Amoco Corporation (Charles Kulpa, UND) 

MTBE Biodegradation by Pure Cultures. 

Isolation of pure and mixed bacterial strains capable of degrading MTBE in soil and water 
[ongoing; see Mo et al., Biodegradation of methyl t-butyl ether by pure bacterial cultures, 

Appl. Microbiol. Biotechnol. 47: 69-72, 1996]. 

Contaminant Removal; Transport; Transformation 

University of Oklahoma; American Petroleum Institute (Bruce Bauman, API) 

Anaerobic Biodegradation of Gasoline Hydrocarbons and Oxygenates. 

Summarize results of previous research on anaerobic processes and continue to evaluate 
anaerobic biodegradation of dissolved hydrocarbons, whole gasoline, and oxygenates [drafts of 
papers expected March 1999]. 

Contaminant Removal 


58 


University of Texas-Austin; American Petroleum Institute (Robert Mace, UT; Bruce 
Bauman, API) 

Spatial and Temporal Variability of MTBE Plumes in Texas 

Characterize spatial and temporal variation of MTBE plumes and their relation to other 
dissolved hydrocarbons, the nature of the release source, and site hydrogeology using existing 
database of 361 Texas UST sites [expected completion fourth quarter 1998]. 

Transport; Transformation 

University of Washington (Crispin H. Pierce) 

Toxicokinetics of Ethyl Tertiary-butyl Ether 

Develop quantitative, predictive models that account for person- and gender-specific factors that 
influence ETBE toxicokinetics, using controlled exposures to stable isotope-labeled and 
unlabeled compounds and accurate measurements of these compounds and metabolites in blood, 
breath, and urine [ongoing]. 

Health Effects 

University of Washington; American Petroleum Institute (Lee Newman, UW; Bruce Bauman, 
API) 

Phytoremediation of MTBE. 

Evaluate capabilities of selected plants to take up, degrade, or transpire MTBE [expected 
completion late 1999]. 

Contaminant Removal 

University of Waterloo; American Petroleum Institute (Doug Mackay, UW; Bruce Bauman, 
API) 

MTBE Natural Attenuation Field Research, Phase 1. 

Identify suitable research site and generate initial site characterization data to determine: 

1) mass flux of MTBE from a release site and its influence on the size of the resultant dissolved 
phase plume; and 2) natural attenuation processes that act to limit the migration of dissolved 
MTBE at that site [ongoing through 2000; interim reports expected annually]. 

Transport; Transformation 

University of Waterloo; American Petroleum Institute (Jim Barker, UW; Bruce Bauman, API) 
Monitoring Border Aquifer Plume. 

Monitoring of MTBE, BTEX, MeOH, NaCl in experimental plume at Canada Forces Base 
Borden, Ontario; began ca. 1988, tracked for 16 months, resumed in 1996 [expected completion 
fourth quarter 1998; e.g., see Schirmer and Barker, A study of long-term MTBE attenuation in 
the Borden Aquifer, Ontario, Canada, Ground Water Monit. Rem. 18: 113-122, 1998]. 

Transport; Transformation 


59 


University of Wurzburg; Health Effects Institute (Wolfgang Dekant, WW; Maria Costantini, 
HEI) 

Comparative Biotransformation of MTBE, ETBE, TAME, and DIPE in Rats and Humans. 
Compare relative excretion of ether metabolites in humans and rats exposed in vitro and in vivo 
via inhalation, with attention to individual differences [ongoing through 1998]. 

Health Effects 

U.S. Centers for Disease Control and Prevention (David L. Ashley) 

Blood Levels of MTBE and TB A. 

As part ofNHANES IV, determine a reference range of blood levels of MTBE and TBA in 
non-occupationally exposed U.S. residents and examine relationship of these levels to local 
MTBE usage in gasoline and presence of MTBE in household water samples [pilot work begins 
January 1999; survey begins April 1999]. 

Exposure 

U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic 
Substances (Catherine Roman, EPA-OPPTS-CCD) 

Proposed Children's Health Test Rule. 

Toxicity testing of selected chemicals, including MTBE and TBA, with exposure potential for 
children [draft proposed rule in preparation; notice of proposed rule making expected March 
1999 and final rule December 1999]. 

Health effects 

U.S. Environmental Protection Agency, Office of Research and Development (Thomas F. 
Speth, EPA-ORD-NRMRL) 

Cost Comparison of MTBE Removal Technologies. 

Evaluation of ozone/peroxide oxidation and air stripping technologies for MTBE removal; air 
stripping to include off-gas control by adsorption and pilot-scale experiments [expected 
completion 2000]. 

Contaminant Removal 

U.S. Environmental Protection Agency, Office of Research and Development (Fran Kremer, 
EPA-ORD-NRMRL) 

Natural Attenuation of MTBE in Ground Water and Soils. 

Field and laboratory studies on UST sites impacted with MTBE; preparation of technical 
resource documents on natural biodegradation of MTBE and associated HCs in ground water 
and soils, and on the potential for enhanced biodegradation [ongoing]. 

Transport; Transformation; Contaminant Removal 

U.S. Environmental Protection Agency, Office of Research and Development (John Wilson, 
EPA-ORD-NRMRL) 

Natural Attenuation of MTBE. 

Field and laboratory study evaluating the role of natural attenuation of MTBE in a fuel plume at 
Elizabeth City, NC, and other sites [ongoing; report due FY2000]. 

Transport; Transformation 


60 


U.S. Environmental Protection Agency, Office of Research and Development (James Prah, 
EPA-ORD-NHEERL) 

Human Pharmacokinetics of MTBE. 

Pharmacokinetics study of human volunteers given multiple acute exposures to MTBE by 
inhalation, oral, and dermal routes [scheduled completion 1999]. 

Health Effects 

U.S. Environmental Protection Agency, Office of Research and Development (Jim Weaver, 
EPA-ORD-NERL) 

Simulation of Multicomponent Gasoline Dissolution. 

Aquifer transport, leaching, and chemical property estimation models used to study 
multicomponent dissolution from MTBE- and non MTBE-gasolines, effects of MTBE on 
dissolution of BTEX, and minimum number of components required to simulate dissolution of a 
given gasoline component [report expected May 1999]. 

Transport; Transformation 

U.S. Environmental Protection Agency, Office of Research and Development (Peter Gabele, 
EPA-ORD-NERL) 

Marine Engine Emissions Characterization. 

Characterize emissions in air and water from small outboard (<15hp) engines using 12%-vol 
MTBE-gasoline [expected completion fall 1999]. 

Source Characterization 

U.S. Environmental Protection Agency, Office of Research and Development; IT 
Corporation (Anthony Tafuri, EPA-ORD-NRML) 

Technologies for Remediating Petroleum-contaminated Soil. 

Studies (bench and pilot held) of hydrogen peroxide with Fenton’s reagent to oxidize MTBE in 
soil and water; identify intermediate products that may develop in treatment process and 
determine operational parameters (Chen et al., Chemical oxidation treatment of petroleum 
contaminated soil using Fenton’s reagent, J. Environ. Sci. and Health, A33: 987-1008, 1998) 
[ongoing]. 

Contaminant Removal 

U.S. Environmental Protection Agency, Office of Research and Development; New York 
State Department of Environmental Conservation (Jim Weaver, EPA-ORD-NERL; Joseph 
Haas, NY DEC) 

Modeling Plume: East Patchogue and Uniondale. 

3-D monitoring and modeling of MTBE, BTEX in contaminant plume from UST site on Long 
Island, NY, a demonstration site for EPA Hydrocarbon Spill Screening Model (HSSM) 

[J. Weaver, Transport and transformation of BTEX and MTBE in a sand aquifer, Ground Water 
Monit. Remed. (accepted); additional report in preparation]. 

Transport; Transformation 


61 


U.S. Environmental Protection Agency, Office of Research and Development; U.S. 
Environmental Protection Agency-Region 9 (Lance Wallace, EPA-ORD-NERL; Henry Lee, 
EPA-Region 9) 

MTBE Exposure During Showering. 

Personal exposure measurements of MTBE in shower microenvironment [expected to begin 
1999]. 

Exposure 

U.S. Geological Survey; American Petroleum Institute (Art Baehr, USGS; H. Hopkins, API) 
Modeling Groundwater Impacts from MTBE Vadose Zone Transport. 

Determine minimum mass source in vadose zone to create a persistent oxygenate impact to 
groundwater [begin December 1998; expected completion second quarter 1999]. 

Occurrence; Source Characterization 

U.S. Geological Survey-NAWQA (John Zogorski, Wayne Lapham, USGS) 

National Retrospective Analyses: Selected Areas. 

Retrospective analysis ofVOC and limited MTBE data in about 20 U.S. areas: CA, ID, I A, NJ, 
NY, TX, WI; several other areas available for further analyses; additional data being sought for 
1998-1999 [ongoing through 2000; findings published yearly 
(see http://wwwsd.cr.usgs.gov/nawqa/pubs/)]. 

Occurrence; Source Characterization 

U.S. Geological Survey-NAWQA (Mary Ann Thomas, USGS) 

Groundwater Monitoring: Michigan. 

Characterization of groundwater in residential suburban Detroit area 1996-1998; preliminary 
data analysis did not indicate presence of MTBE or TBA [data release expected mid-1999 
(see http://wwwsd.cr.usgs.gov/nawqa/pubs/)]. 

Occurrence; Source Characterization 

U.S. Geological Survey-NAWQA (Arthur Baehr, Mark Ayers, USGS) 

Glassboro Comprehensive Urban Study. 

Monitor MTBE, VOCs in air, precipitation, surface water, unsaturated zone, ground water in 
Glassboro, NJ area aquifer [ongoing 1996-2000; project description published; shallow 
groundwater VOC data published; research published periodically 
(see http://wwwsd.cr.usgs.gov/nawqa/pubs/)]. 

Transport; Transformation; Source Characterization 

U.S. Geological Survey-NAWQA (John Zogorski, USGS) 

Monitoring Urban Storm Water: Selected Areas. 

Monitor urban storm water for VOCs, including MTBE, in 16 U.S. metropolitan areas: Boise, 
Phoenix, Colorado Springs, Denver, San Antonio, Dallas, Omaha, Independence, Little Rock, 
Davenport, Baton Rouge, Mobile, Huntsville, Birmingham, Montgomery, Atlanta [reports 
available upon request (see http://wwwsd.cr.usgs.gov/nawqa/pubs/)]. 

Occurrence; Source Characterization 


62 


U.S. Geological Survey-NAWQA; U.S. Environmental Protection Agency-Office of Water 

(Steve Grady, USGS; Mike Osinski, EPA-OW) 

Retrospective Analyses: New England-Mid Atlantic. 

Retrospective data analysis for MTBE and other VOCs in ground/drinking water in 12 southern 
New England and Mid-Atlantic states; focus primarily on ambient ground water and PWS 
drinking water data for MTBE and other VOCs, with one objective to create protocol for state 
drinking water quality data collection [design completed; retrospective approximately 50% 
complete; report expected late 1999 (see http://wwwsd.cr.usgs.gov/nawqa/pubsf)]. 

Occurrence; Source Characterization 

U.S. Geological Survey-NAWQA; Oregon Graduate Institute (John Zogorski, USGS; 

Jim Pankow, Wes Jarrell, OGI) 

Plant Transpiration. 

Measurement of plant transpiration on VOC levels including MTBE [report and journal article 
expected 1999 (see http://wwwsd.cr.usgs.gov/nawqa/pubs/)]. 

Transport; Transformation 

U.S. Geological Survey-NAWQA; Oregon Graduate Institute; University of Washington 

(John Zogorski, USGS; Jim Pankow, OGI; Bill Asher) 

VOC Behavior and Fate. 

Modeling the behavior and fate of VOCs including MTBE in PWS reservoirs [journal article and 
report expected 1999 (see http://wwwsd.cr.usgs.gov/nawqa/pubs/)]. 

Transport; Transformation 

U.S. Geological Survey-NAWQA (Paul Squillace, Mike Moran, John Zogorski, USGS) 
Occurrence of MTBE and Other VOCs in Ambient Groundwater. 

VOCs in groundwater of the United States, 1985-1995 [journal article in preparation 
(see http://wwwsd.cr.usgs.gov/nawqa/pubs/)]. 

Occurrence 

U.S. Geological Survey-NAWQA; Oregon Graduate Institute (John Zogorski, USGS; Jim 
Pankow, Rick Johnson, OGI) 

Modeling MTBE Transport to a Production Well. 

Preliminary evaluation of factors that influence the capture of MTBE UST release by a 
hypothetical production well [article expected early 1999 
(see http://wwwsd. cr. usgs.gov/nawqa/pubs/)]. 

Transport; Transformation 

U.S. Geological Survey-NAWQA; Oregon Graduate Institute (John Zogorski, USGS; 

Jim Pankow, OGI) 

VOC Analytic Methods: Air. 

Analytic methods developed for VOCs, including MTBE, TAME, DIPE, and ETBE, in ambient 
air [article to appear in Analytical Chemistry , late 1998 or early 1999 
(see http://wwwsd.cr. usgs.gov/nawqa/pubs/)]. 

Occurrence (Analytic Methods) 


63 




U.S. Geological Survey; Oregon Graduate Institute (John Zogorski, USGS; James Pankow, 
OGI) 

Degradation Assessment. 

Determine degradation pathways, by-products, kinetics, and their relationship to varied 
geological environments for MTBE, TBA, TBF, TAME, TAA, and acetone based on monitoring 
data from several plumes and lab studies [field monitoring and lab studies continuing in 1998; 
project findings and lab analytical method published 
(see http://wwwsd.cr.usgs.gov/nawqa/pubs/)]. 

Transport; Transformation 

U.S. Geological Survey; Oregon Graduate Institute (John Zogorski, USGS; James Pankow, 
OGI) 

Modeling Non-point Source Inputs. 

Modeling of atmospheric and land-based non-point source inputs of MTBE to ground water 
systems (see also USGS: Glassboro comprehensive urban study) [ongoing 1996-2000; research 
published periodically (see http://wwwsd.cr.usgs.gov/nawqa/pubs/)]. 

Source Characterization; Occurrence; Transport; Transformation 

U.S. Geological Survey-Toxics Hydrology Program (Herb Buxton, John Zogorski, 

J. Landmeyer) 

Monitoring Plume: Beaufort, SC. 

Ongoing monitoring of shallow ground water and unsaturated zone above the ground water 
plume for VOCs, including MTBE, BTEX, TBA, for movement and degradation since 1991 at 
Laurel Bay UST (Beaufort Marine Corps Air Station, SC); remediated 1993; flow and 
contaminant modeling; long-term hydrology study site [ongoing; project scope and findings 
through 1997published (see http://wwwsd.cr.usgs.gov/nawqa/pubs/)]. 

Transport; Transformation 

U.S. Geological Survey (Carol Boughton) 

Survey of Man-Made Organic Compounds in Lake Tahoe and Selected Tributaries, 
Califomia-Nevada 1998-99. 

Sample multiple sites on Lake Tahoe and major tributaries for the presence of organochlorine, 
semi-volatile industrial, synthetic-hydrocarbon compounds (including MTBE) and soluble 
pesticides [results expected to be published in 1999 
(see http://wwwsd.cr.usgs.gov/nawqa/pubs/)]. 

Occurrence 

Western States Petroleum Association (Jeff Sickenger) 

Well Purging Study: California. 

Comparison of MTBE, BTEX, and TPH-g in groundwater samples before and after purging at 
CA wells: concentrations higher before than after purging, variability of before/after 
concentrations comparable to variability between purging methods; high variability in small 
population of sites due to site-specific conditions [completed (Final Report: the California 
groundwater purging study for petroleum hydrocarbons, SECOR International, Inc., 1996; 
Lundegard et al., Net benefit of well purging reevaluated, Environ. Geosci. 4: 111-118, 1997; 


64 


see http://www.secor.com/purge/purge.htm) ; however, also see: Flood, F., New study advocates 
no purging prior to sampling, http://www.grac.org/spring97/article2.htm]. 

Contaminant Removal; Transport; Transformation 

Woodward-Clyde; American Petroleum Institute (R. Claff, API) 

Occurrence, Treatment, and Impact of Oxygenates in Effluents. 

Characterize and quantify presence of oxygenates in petroleum marketing terminal and refinery 
wastewater streams and treatment processes; identify and quantify fate of oxygenates in terminal 
and refinery wastewater treatment facilities [expected completion late 1999]. 

Occurrence; Transport; Transformation 

World Health Organization - IPCS (Edward Smith, WHO Geneva) 

Environmental Health Criteria for MTBE. 

Critical review of effects of MTBE on human health and the environment [in press]. 

Assessment 


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